The energy of a photon, whose momentum is 10 MeV/c, where c is the speed of light, is given by A. 10 MeV B. 100 MeV C. 1 MeV D. 0.1 MeV

The correct answer is A. 10 MeV.

The energy of a photon is given by the equation $E = pc$, where $p$ is the momentum of the photon and $c$ is the speed of light. In this case, $p = 10$ MeV/c, so $E = (10$ MeV/c)$c = 10$ MeV.

Option B is incorrect because it is 10 times the actual energy. Option C is incorrect because it is 100 times less than the actual energy. Option D is incorrect because it is 10 times less than the actual energy.