In a Certain Particle Accelerator, a Current of 800 μA

In a certain particle accelerator, a current of 800 μA is carried by a 6.00-MeV proton beam that has a radius of 1.50 mm. The mass of a proton is 1.67 × 10^-27 kg. How many protons per unit volume are in this beam?

A) 3.24 × 10¹³ protons/m³
B) 7.76 × 10¹³ protons/m³
C) 1.57 × 10¹³ protons/m³
D) 2.09 × 10¹³ protons/m³
E) 4.34 × 10¹³ protons/m³