Explanation

(c)
Stronger the base, higher the tendency to accept protons. Among the given, $CH_{3}COOH$ and $H_{2}S$ both are acids, thus have very low tendency to accept a proton. Between $NH_{3}$ and $H_{2}O,\ NH_{3}$ is a stronger base (due to less electronegativity of N as compared to O) and hence, it has the highest tendency to accept a proton among the given. Moreover, the conjugate base formed by it also stable one
$NH_{3} + H^{+} \rightarrow NH_{4}^{+}$
(stable)