For the following question(s), consider the following reaction mechanism:
Step 1 2X + Y W + 2Z fast
Step 2 W + Z W + U + V slow
Step 3 V + Z 2 W + Y fast
Refer to Exhibit 11-2. The rate-limiting step in this reaction is Step _____, because _____.
a. 3; the last step is always the rate-limiting step
b. 1; it is bimolecular
c. 1; the first step must occur before any others can occur
d. 2; it is the slow step
e. 2; it uses a product of the first step