In a Certain Particle Accelerator, a Current of 300 μA

In a certain particle accelerator, a current of 300 μA is carried by a 4.00-MeV proton beam that has a radius of 1.30 mm. The mass of a proton is 1.67 × 10^-27 kg. If the beam hits a target, how many protons hit the target in 3 s?

A) 1.55 × 10¹⁵
B) 8.64 × 10¹⁵
C) 3.42 × 10¹⁵
D) 4.29 × 10¹⁵
E) None of these is correct.