The electric field in a region is radially outward with magnitude $E=A\;r\;$ . Find the charge contained in a sphere of radius a centered at the origin . Take $\;A=90\;Vm^{-2}\;$ and $\;a = 2m\;$

Question

$(a)\;8 \mu C\qquad(b)\;0.8 \mu C\qquad(c)\;0.08 \mu C\qquad(d)\;80 \mu C$