Consider the S_N2 Reaction of 2-Iodopentane with CH₃CO₂^- Ion

Consider the S_N2 reaction of 2-iodopentane with CH₃CO₂^- ion. Assuming no other changes, what effect on the rate would result from simultaneously doubling the concentrations of both 2-iodopentane and CH₃CO₂^- ion?

A) no effect
B) double the rate
C) triple the rate
D) rate would increase by four times
E) rate would increase by six times