Electrons in a Certain Laser Make Transitions from a Metastable

Multiple Choice

Electrons in a certain laser make transitions from a metastable state to the ground state.Initially there are 6*10²⁰ atoms in the metastable state and 2 * 10²⁰ atoms in the ground state.The number of photons that can be produced in a single burst is about:

A) 2 * 10²⁰
B) 3 *10²⁰
C) 4 * 10²⁰
D) 6 *10²⁰
E) 8 * 10²⁰