An Electron-Positron Pair Traveling Towards Each Other with a Speed $\rarr$

Multiple Choice

An electron-positron pair traveling towards each other with a speed of 0.95 c with respect to their center of mass,collide and annihilate according to e^- + e⁺ $\rarr$ $\gamma$ + $\gamma$ .Assuming the observer is at rest with respect to the center of mass of the electron-positron pair,what is the frequency of the photons?

A) 9.89 * 10¹⁹ Hz
B) 9.02 * 10¹⁸ Hz
C) 5.13 * 10²⁰ Hz
D) 7.25 * 10¹⁹ Hz
E) 3.95 * 10²⁰ Hz