An Electron-Ositron Pair Can Annihilate with the Emission of Two $\gamma$

Multiple Choice

An electron-ositron pair can annihilate with the emission of two $\gamma$ -rays. A single (isolated) $\gamma$ -ray cannot disappear with the creation of an electron-positron pair because

A) momentum could not be conserved.
B) energy could not be conserved.
C) angular momentum could not be conserved.
D) Hold it! The premise is wrong: a single (isolated) $\gamma$ -ray can disappear under the circumstances described.