The rest mass of a proton is ${\text{938 MeV}}\,{{\text{c}}^{ - 2}}$. The energy of a proton at rest is

A.     $9.38{\text{ J}}$

B.     $9.38 \times {10^8} \times {(3 \times {10^8})^2}{\text{ J}}$

C.     $9.38 \times {10^8}{\text{ eV}}$

D.     $9.38 \times {10^8} \times {(3 \times {10^8})^2}{\text{ eV}}$

C

Many candidates appeared unfamiliar with the unit ${\text{MeV}}\,{{\text{c}}^{ - 2}}$, despite the fact that the Physics Guide states that students should be familiar with this unit.