The correct option is D 9.6×10−3 A & 9.6×103 A/m2
(a). The total charge crossing a perpendicular cross-section in one second is
q=ne=6.0×1016×1.6×10−19 C
⇒q=9.6×10−3 C
So, current will be
I=qt=9.6×10−3 C1 s=9.6×10−3 A
As the charge is negative, the current is opposite to be direction of motion of the beam.
(b). The current density is defined as
J=IA=9.6×10−3 A(1.0 mm)2=9.6×10−3A1.0×10−6m2
⇒J=9.6×103 A/m2
Hence, option (a) is correct.