The correct answer is $\begin{array}{llll} A & B & C & D \end{array}$

(a) $\mathrm{B}_2 \mathrm{H}_6$ is an electron deficient compound in Lewis terms, since two electrons are less available per bond and has 3-centre-2-electron bond in it. (b) $\mathrm{CH}_4$ is an electron precise hybrid since in this the number of electrons present is equal to the number of electrons required. (c) $\mathrm{PH}_3$ is an electron rich hybride in which the number of electrons present are more than the number of electrons required for making octet. (d) $\mathrm{CaH}_2$ is a saline hybride, since its structure is salt like.