In game theory,the credibility of a threat:

A) determines whether or not a Nash equilibrium to a game exists.
B) influences the degree of cooperation between two rivals.
C) is relevant only in simultaneous games.
D) determines whether or not a firm has a dominant strategy.

The credibility of a threat can influence the degree of cooperation between two rivals. If a player believes that their opponent's threat is not credible, they may choose to ignore it and not modify their behavior accordingly. However, if the threat is credible, the player may modify their behavior to avoid the negative consequences of the threat. Therefore, in games where threats are made, the credibility of those threats can impact the outcome of the game.