Explanation

(a)
Only aldehydes react with both Tollen’s reagent and Fehling’s solution
$CH_{3}CHO\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ CH_{3}COOH$
(a) (b)
Aldehyde acid
$CH_{3}COCH_{3}\ \ \ \ \ \ \ \ \ \ \ \ \ \ CH_{3}CH_{2}COOH$
(c) (d)
Ketone acid
$CH_{3}CHO\$ (ethanal) is the only aldehyde in given choices.
So, it reacts with both Tollen’s reagent and Fehling solution.
$CH_{3}CHO +$Ammoniacal $AgNO_{3} \rightarrow Ag$ mirror
(Tollen’s reagent)
$CH_{3}CHO + Cu^{2 +}$ions complexed$\rightarrow Cu_{2}O$
With tartarate anion red ppt.