Photons in a Laser Beam Have the Same Energy, Wavelength

Multiple Choice

Photons in a laser beam have the same energy, wavelength, polarization direction, and phase because:

A) each is produced in an emission that is stimulated by another
B) all come from the same atom
C) the lasing material has only two quantum states
D) all photons are alike, no matter what their source
E) none of the above