Answer:
Option A, CH3COOH
Step-by-step explanation:
An organic acid is one that has carboxyl group i.e – COOH.
On rearranging all the given chemical compounds, following are obtained
a) CH3COOH – This compound has a carboxyl group in it and thus it can be re written as CH3-COOH.
b) C2H6O – This compound has a hydroxyl group (OH) and thus it can be re written as C2H5-OH
c) C2HO – This compound has a keto group (C-O) and thus it can be re written as O-C-H2
d) CH4 – This is normal hydrocarbon and is commonly known as methane.
Among all the given options, only option A has a carboxyl group. Thus , it is an organic acid.