What's the most common way for a central bank to reduce the money supply?

Refer to the above figure. The figure gives the payoff matrix for two individuals who are being accused of robbing a bank together. What is dominant strategy for Bob?

A) Confess. B) Don't confess. C) Flip a coin to decide what to do. D) There is no dominant strategy.

"Ceteris paribus" assumption means

A) the role of rational self-interest in the economy. B) that nothing else changes except the variables under consideration. C) relying on real-world data in evaluating the usefulness of a model. D) analysis that is strictly limited to making purely positive statements.