Self- Interest Makes Cartels Unstable for All of the Following

Self- interest makes cartels unstable for all of the following reasons except which one?

A) Each firm has the incentive to produce more than the agreed upon quantity.
B) Each firm has an incentive to be the whistle- blower.
C) Each firm has the incentive to lower their costs by producing less than the agreed upon quantity.
D) Each firm has an incentive to be the first to report and confess cartel behavior.