In a Second Order Reaction

In a second order reaction:
I. the sum of the exponents in the rate law is equal to two.
II. at least one of the exponents in the rate law is a two.
III. the half-life is not constant.
IV. the half-life is constant.
V. k can be expressed as M^-2s^-1 or M^-2min^-1.

A) I and IV
B) II and IV
C) I, III, and V
D) I and III
E) II and III