The placenta is an endocrine gland, that is only present during pregnancy. It produces hormones including human chorionic gonadotropin (hCG), progesterone, estrogen, and human placental lactogen (hPL).

Prolactin is a hormone secreted in mammals (lactotrophs), usually females and stimulates the mammary gland to produce milk. This hormone is also called luteotropin or luteotropic hormone. The major source of prolactin is the anterior pituitary regulated by the hypothalamus, however, several other tissues synthesize and secrete this hormone. All the other hormones in the options such as hCG, hPL, and estrogen are secreted by the placenta.

Placenta acts as a barrier between the mother and foetus and is a temporary association between the foetal and maternal tissues. It acts as an endocrine gland and secretes hormones such as human Chorionic Gonadotropin (hCG), chorionic corticotropin, oestrogens and progesterone.

The placenta is a cushion like tissue which supports the embryo and facilitates the supply of oxygen and nutrients to the embryo and also the removal of carbon dioxide and excretory waste materials produced by the embryo. It also acts as an endocrine tissue and produces several hormones like human chorionic gonadotropin, human placental lactogen, estrogens, progesterone, and relaxin etc.

A) Testosterone is the male hormone which helps in the formation of sperms and male secondary sexual characters. 

Human chorionic hormone (hCG) is placental hormone concerning with maintenance of pregnancy. 

• GH and ACTH are secreted by the cells of the anterior pituitary.
• Gastrin hormone is produced by the parietal cells of the stomach and aids in gastric mobility.
• The growing placenta produces progesterone prevents the shedding of the uterine lining since this would result in pregnancy loss. It also suppresses the ability of the muscular layer of the uterine wall to contract, which is important in preventing labour from occurring before the end of pregnancy.
• So, the correct option is 'Progesterone'.

During implantation of the zygote in the uterus, the chorionic villi and the uterine endometrium become interdigitated with each other and form the placenta. The placenta supplies oxygen/nutrients to the developing fetus and also removes carbon dioxide and waste products from the fetus. Placenta also acts as an endocrine tissue and secretes several hormones like Human Chorionic Gonadotropin (hCG), human placental lactogen (hPL), estrogen, progesterone etc.

The placenta is an organ, that connects the developing fetus to the uterine wall to allow nutrient uptake, waste elimination etc. hCG is human chorionic gonadotropin hormone, that can be found in maternal blood and urine shortly after implantation has occured. hCG is present only during pregnancy as it is secreted by the placenta. The syncytical layer of chorionic villi of placenta secretes hCG.
Thus, the correct answer is option (D).

• The hormone human chorionic gonadotropin (hCG) is produced during pregnancy.
  
• It is made by cells formed in the placenta, which nourishes the egg after it has been fertilized and becomes attached to the uterine wall.
  
• Its levels can first be detected by a blood test about 11 days after conception and about 12-14 days after conception by a urine test.
  

The placenta produces two steroid hormones, Estrogen and Progesterone along with a few proteinaceous hormones which include human chorionic gonadotrophin (hCG), human placental lactogen (hPL), placental growth hormone, relaxin and kisspeptin. These hormones function to support pregnancy during the gestation period.

Human chorionic gonadotrophin is a hormone secreted by the placenta during pregnancy. It is a pregnancy indicating hormone.

hCG (Human Chorionic Gonadotrophins), hPL (Human Placental Lactogen), hCS (human Chorionic somatomammotropin) are the hormones secreted by placenta so they are released during pregnancy only as the placenta is formed in pregnancy only. Placenta release other hormones as Estrogen and progesterone but these hormones are released by ovaries even in non-pregnant females. Therefore, hCG, hPL, and hCS are exclusively released in pregnancy from placenta.

The placenta facilitates the supply of oxygen and nutrients to the embryo and also the removal of carbon dioxide and excretory/waste materials produced by the embryo.

The signals for parturition originates from the fully developed foetus and placenta, which induce mild uterine contractions called as foetal ejection reflex. This triggers the release of oxytocin, which is birth hormone from the maternal pituitary gland. This oxytocin starts a series of powerful contractions in the uterus to help expel the baby and limits bleeding of the placenta near the entry of the vaginal canal.
Thus, the correct answer is option (C).