In the given reactions identify $A$ and $B$

Solubility of calcium phosphate (molecular mass, M) in water is $\mathrm{W_{g}}$ per $100 \mathrm{~mL}$ at $25^{\circ} \mathrm{C}$. Its solubility product at $25^{\circ} \mathrm{C}$ will be approximately.

Given below are two statements :

Statement (I) : $\mathrm{SiO}_2$ and $\mathrm{GeO}_2$ are acidic while $\mathrm{SnO}$ and $\mathrm{PbO}$ are amphoteric in nature.

Statement (II) : Allotropic forms of carbon are due to property of catenation and $\mathrm{p} \pi-\mathrm{d} \pi$ bond formation.

In the light of the above statements, choose the most appropriate answer from the options given below :

The set of meta directing functional groups from the following sets is :