A pragmatist is someone who beleives only facts. A conservative is a persn who does not welcome change.

 Precocious is a person who is gifted beyond years. All other words represent uncultured persons.

Ingenuous is someone who is frank and sincere. Candid means the same.

 Paranoid is usually associated with excessive suspicion of the motives of others.

 Orthodox is a person having conservative beliefs; all other words represent gloomy demeanour.

 Vulturous is greedy; generous is the opposite in meaning.

 The lead pair is a set of antonymous words: a crafty person lacks simplicity and strightforwardness. Similarly lecherousness is a trait extraneous to and opposite of the nature of a celibate (a person who indulges in abstinence).

The root word here is 'ego', which means 'I'. An egomaniac is one who is obsessed with himself to the extent of being dangerous, an egophobic is afraid of himself and an alter ego is someone who is just the same as one. The person who thinks and talks about himself is known as an egoist.

 Complacency (Com + Plac  = together + pleased) is a state of satisfaction with how things are. Only (2) represents such state. 

 An apostate is a person who forsakes his own cause, party or religion. None of the options, except option 1 has illustrated this feature.

 An inerudite person lacks knowledge; an indecisive person lacks determination.

 A pair of antonyms. A libertarian (lax) is not exacting (strict); a prodigy (genius) is not doltish (dull). 

 Aesthete is a worldly person with a sense of beauty. All other words represent simplicity or renunciation of worldly pursuits.

 Fiction belong o the category of literature.

 Ham and Pork  are terms for the meat of a pig, scallops is a sea food. The correct word is 'venison'.

 'Paedetrician' is a doctor who specializes in treating children. The root word here is 'Paed', which means 'child' (peedophile).

 A pair of synonyms. Saturnine is surly or morose; convivial is lively.

 A hypochondriac shows lot of anxiety (false feeling of sickness); a martinet shows lot of strictness in matters of discipline.

 A pair of antonyms. Idyllic represents a pastoral laid-back approach. Frenzied or agitaed will be the opposite. Likewise, hermetic represents abstinence while prurient represents not only indulgene but also lewdness. 

 A paranoid person is someone who is always anxious or afraid. An ascetic is a person who renounces the worldly benefits for spritual peace. 

 Cynical is an adjective used to describe someone who is bitter and distrustful of everyone and is contemptuous.

 Scurrilous means 'highly abusive and derisive'.

 This word is usually used in reference to 'noisy and unruly children'. 

 Pastoral pertains to the country or life in the country which is simple.

 The meaning of the sentence suggests that the missing word should have a positive connotation to it, hence, option 1 and 3 are incorrect. The correct answer is 'affable', which means 'courteous and polite in disposition'.