Explanation

(c)
When a carbonyl compound having the structure $CH_{3} - CO - R$ is reacted with a halogen in the presence of $NaOH,\ KOH,\ Na_{2}CO_{3}or\ K_{2}CO_{3}$ solution, haloform is obtained. Thus, butanone-2 gives +ve iodoform test.
$CH_{3} - CH_{2} - C - CH_{3}\underset{(Iodoform\ test)}{\ \overset{{\ \ \ \ \ \ \ \ \ \ I}_{2}/NaOH\ \ \ \ }{\rightarrow}}$
$\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \parallel \$
O
2-butanone
$\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ O\ \ \ \ \ \ \ \ \$
$\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \parallel$
$CHI_{3} + CH_{3} - CH_{2} - C - ONa$
iodoform