The correct option is
C Both A and B
Iodoform test is used to check the presence of carbonyl compounds with the structure
R−CO−CH3 or alcohols with the structure
R−CH(OH)−CH3 in a given unknown substance.
When Iodine and sodium hydroxide are added to a compound that contains either a methyl ketone or a secondary alcohol with a methyl group in the alpha position, a pale yellow precipitate of iodoform or triiodomethane is formed. It can be used to identify aldehydes or ketones. If an aldehyde gives a positive iodoform test, then it must be acetaldehyde since it is the only aldehyde with a
CH3C=O group.
∴ Ethanol shows positive iodoform test.
Acetaldehyde also shows + ve iodoform test.
But in
CH3OH and HCHO, there will be no possibility for the formation of
group to give CH
I3. C and D show negative iodoform test.
Hence, the correct option is (c).