What Is the Role of PCl₃ in the Following Reaction

What is the role of PCl₃ in the following reaction?

A) It converts the carboxylic acid to an enolizable acid chloride.
B) It acts as a base and deprotonates the α carbon.
C) It converts the carboxylic acid to an acid bromide.
D) It activates Br₂ and forms a better nucleophile.
E) It increases the rate of the reaction.