The molecular structure depicted in the question contains a carbonyl group ($\text{C}=\text{O}$) bonded directly to at least one hydrogen atom (specifically $\text{H}-\text{CHO}$, formaldehyde or methanal):
Compounds containing the formyl group ($-\text{CH}=\text{O}$) where carbonyl carbon is terminal and bonded to hydrogen are classified as Aldehydes.
A Ketone has the carbonyl group bonded to two carbon atoms ($R-\text{CO}-R'$).
A Carboxylic acid has a hydroxyl group attached to the carbonyl carbon ($-\text{COOH}$).
An Amide has an amino group attached to the carbonyl carbon ($-\text{CONH}_2$).

In organic chemistry nomenclature, when a benzene ring ($ ext{C}_6 ext{H}_6$) loses one hydrogen atom to attach as a functional branch or substituent group to a parent carbon chain, the resulting univalent aromatic radical ($-\text{C}_6 ext{H}_5$) is designated as the Phenyl group (abbreviated $-\text{Ph}$ or $\phi$).
(Phenol is the hydroxy derivative $\text{C}_6 ext{H}_5\text{OH}$; Imidazole is a five-membered heterocyclic diazole ring).

General molecular formulas for aliphatic hydrocarbon homologous series:
Alkanes (saturated hydrocarbons with single $\text{C}-\text{C}$ bonds): $\text{C}_n\text{H}_{2n+2}$
Alkenes (hydrocarbons with one $\text{C}=\text{C}$ double bond): $\text{C}_n\text{H}_{2n}$
Alkynes (hydrocarbons with one $\text{C}\equiv\text{C}$ triple bond): $\text{C}_n\text{H}_{2n-2}$

For the primary four-carbon straight-chain alcohol $\text{CH}_3\text{CH}_2\text{CH}_2\text{CH}_2\text{OH}$ (IUPAC name: butan-1-ol):
The traditional common name is n-butyl alcohol (Option 2).
It is also universally designated by the common name n-butanol (Option 3).
Because both 'n-butyl alcohol' and 'n-butanol' represent standard accepted non-systematic/common names for this compound, NTA officially credited both Option 2 and Option 3 in the final answer key (Key: 2&3).