It Is Easier to Sustain a Collusive Agreement in an Infinitely

It is easier to sustain a collusive agreement in an infinitely repeated game if:
I. The present value of the stream of payoffs from cooperating is lower.
II. The discount rate is lower.
III. The present value of violating the agreement is higher.
Which of the following is correct?

A) I only.
B) II only.
C) III only.
D) I and II only.
E) I and III only.