The correct option is C. Ethanol is alcohol and is a primary $1$ degree monohydric alcohol with moleculer formula $C _2H _5OH.$

$\overset{3}{C}H _3-\overset{2}{\underset{CH _3}{\underset{|}{CH}}}-\overset{1\,\,\,\,\,}{CH _2}-OH$

$-OH$ (Hydroxyl group) is the functional group of alcohol. Because, if we add $-OH$ to a Methyl group $(-CH _3)$, it will be converted to Methyl alcohol $(CH _3OH)$

$2,4,6-trinitrophenol$ is picric acid while, $2,4,6-trinitrotoluene$ is $TNT$.

${ CH } _{ 3 }^{ 3 }{ CH } _{ 2 }^{ 2 }{ CH } _{ 2 }^{ 1 }{ OH }$
Carbon with functional group gets position 1. Therefore, IUPAC name is Propan-1-ol.

$CH _{3}-CH(CH _{3})-CH _{2}-OH$ is a primary alcohol as hydroxal group; -OH is attached to the primary carbon.

Picric acid is 2,4,6-trinitrophenol. It is yellow crystalline solid. It is an explosive. Wet picric acid is used as a skin dye reacting with proteins in skin to give dark brown color.

$(CH _3) _2CHOH$ is 2-propanol or isopropyl alcohol, $CH _3OH$ is methanol, $CH _3CH _2CH _2OH$ is 1- propanol or isopropyl alcohol.

According to IUPAC system suffix for alcohols is ' ol'

The given compound can be numbered from left to right or vice versa. At the 2nd position, there is a methyl group and is designated as 2-Methyl. 

In this compound, the number of carbon atoms is 3. So, the parent alkane is propane. 

The compound has 2 alcohol groups at C-2 positions on both the sides. From this point we can not say from where to start numbering. But if we number from right hand side there is also a methyl group at C-2 position. So we start number from right hand side.
Since there are two alcoholic group, we use suffix "diol"
Thus IUPAC name is: 2-Methyl-2,4 pentanediol

Longest carbon chain has 6 atoms. We number from right hand side as alcohol group at C-2 gets least number in this case and suffix used for alcohol is "-ol". Methyl group is present at C-4 position.

Thus, IUPAC name is 4-Methyl-2-hexanol.