Which of the Following Statements Is True of a Laser

Multiple Choice

Which of the following statements is true of a laser cavity?

A) A laser cavity consists of four mirrors.
B) All the mirrors in a laser cavity are fully reflective mirrors.
C) In a laser cavity, the first photon hits one of the mirrors and bounces back to pass through the lasting medium again.
D) A chain reaction produces a large number of photons that circulate outside a laser cavity.
E) In a laser cavity, the wavelength of the first photon is different from the wavelengths of the other photons.