Protons Scatter Off a Lead (Pb)nuclei in a Foil Target $\circ$

Multiple Choice

Protons scatter off a lead (Pb) nuclei in a foil target.Each Pb nucleus contains 82 protons.If both the incoming protons and the Pb nuclei can be treated as point objects and the differential scattering cross section for the protons to scatter off the Pb nuclei at an angle of 25 ^$\circ$ relative to their initial velocity is 3.2 *10^-26 m²/sr,what is the initial kinetic energy of the protons?

A) 2.8 MeV
B) 3.5 MeV
C) 3.2 MeV
D) 1.6 MeV
E) 4.2 MeV