Exhibit 12-2 for the Following Question(s), Consider the Following Reaction

Exhibit 12-2 For the following question(s) , consider the following reaction mechanism:
Refer to Exhibit 12-2. The rate-limiting step in this reaction is Step ____, because ____.

A) 3; the last step is always the rate-limiting step
B) 2; it uses a product of the first step
C) 2; it is the slow step
D) 1; it is bimolecular
E) 1; the first step must occur before any others can occur