Suppose N Identical Firms Engage in Bertrand Competition in a Stage

Suppose n identical firms engage in Bertrand competition in a stage game repeated infinitely often.What condition on the discount factor $\delta$ is required for firms to be able to tacitly collude on the monopoly industry output?

A) $\delta \geq 1 / 2$ .
B) $\delta \leq 1 / n$ .
C) $\delta \geq 1 / n ^ { 2 }$ .
D) $\delta \geq 1 - ( 1 / n )$ .