(a) $\mathit{X}$ and $\mathit{Y}$ are the two types of gametes produced by men.
(b) No, $\mathrm{X}$ chromosome is inherited from the mother because to be a male, the child must posses a $\mathrm{Y}$ chromosome which can only be provided by the heterozygous $\left(\mathit{X}\mathit{Y}\right)$ father and not the homozygous $\left(\mathit{X}\mathit{X}\right)$ mother.
(c) Only one type, i.e., $\mathrm{X}$ chromosome carrying egg cell.