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In $HS^-$, $I^-$, $R-NH_2$, $NH_3$, order of proton accepting tendency will be :-
A
$I^- \gt NH_3 \gt R-NH_2 \gt HS^-$
B
$NH_3 \gt R-NH_2 \gt HS^- \gt I^-$
C
$RNH_2 \gt NH_3 \gt HS^- \gt I^-$
D
$HS^- \gt RNH_2 \gt NH_3 \gt I^-$
Detailed Solution
Proton accepting tendency means Brønsted basic strength.
Amines are stronger bases than ammonia, because the alkyl group (+I effect) increases the electron density on nitrogen: $RNH_2 \gt NH_3$.
$HS^-$ is the conjugate base of the weak acid $H_2S$, so it is a moderate base, weaker than ammonia and amines in this comparison.
$I^-$ is the conjugate base of the very strong acid HI, so it has almost no tendency to accept a proton.
So the order is $RNH_2 \gt NH_3 \gt HS^- \gt I^-$.
Amines are stronger bases than ammonia, because the alkyl group (+I effect) increases the electron density on nitrogen: $RNH_2 \gt NH_3$.
$HS^-$ is the conjugate base of the weak acid $H_2S$, so it is a moderate base, weaker than ammonia and amines in this comparison.
$I^-$ is the conjugate base of the very strong acid HI, so it has almost no tendency to accept a proton.
So the order is $RNH_2 \gt NH_3 \gt HS^- \gt I^-$.