Electric field and potential inside hollow charged conducting sphere are respectively

Question

$(a)\; (0 ,0)\qquad(b)\;(0 , \large\frac{k \;q}{r})\qquad(c)\;(\large\frac{k\;q}{r^2} , 0)\qquad(d)\;(\large\frac{k\;q}{r^2},\large\frac{k\;q}{r})$