$9\mathrm{.}8$ Is each of the following definitions valid or invalid? If any is invalid, why?

A$)$ int ivar;

int $*$iptr $=$ &ivar;

B$)$ int ivar, $*$iptr $=$ &ivar;

C$)$ float fvar;

int $*$iptr $=$ &fvar;

D$)$ int nums$[50],*$iptr $=$ nums;

E$)$ int $*$iptr $=$ &ivar;

int ivar;