Explanation

(a)
Fehling solution is cupric ion complex with tartarate anion. Aldehydes reduce it to red precipitate. The red precipitate is chemically $Cu_{2}O$
$\ \ \ \ \ \ \ \ \ \ \ \ \ O$
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$CH_{3} - C - CH_{3}\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ CH_{3}CH_{2}CHO$
acetone propanal
(b)
$CH_{3}COH\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ CH_{3}CH_{2}CH_{2}CHO$
ethanal butanal
(C) (d)
$\therefore\ \$Only acetone which is ketone not an aldehyde does not give iodoform test.