A +100- $\mu$ C Charge Is Placed on the Surface of a Metal

A +10.0- $\mu$ C charge is placed on the surface of a metal shell whose radius is 5.0 cm. The electric field at the center of the shell is

A) zero.
B) 9.0 $\times$ 10⁶ N/C.
C) -9.0 $\times$ 10⁶ N/C.
D) 1.4 $\times$ 10⁵ N/C.