Explanation

(c)
Dissociation of proton from ddd is very difficult due to $–I$ effect of $Cl^{-}$and $N^{+}\$while in $C_{6}H_{5}OH$ due to the reasonance stabilization of phenoxide ion proton eliminates easily. Similarly due to $H$-bonding in $C_{6}H_{5}CH_{2}OH$ it can be eliminate easily and in $CH_{3}C \equiv CH$ the proton is acidic in nature hence, it can be dissociated