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