The Formation of Chlorocarbon Solvents Such as CH₂Cl₂ Proceeds Through $\rarr$

The formation of chlorocarbon solvents such as CH₂Cl₂ proceeds through the reaction of chlorine with methane. Which of the following is a unimolecular reaction in the mechanism?

A) CH₄ + Cl• $\rarr$ CH₃• + HCl
B) H₂ $\rarr$ 2 H•
C) CH₃• + Cl• $\rarr$ CH₃Cl
D) Cl₂ $\rarr$ 2 Cl•
E) CH₂Cl• + Cl• $\rarr$ CH₂Cl₂