B. This answer is incorrect. See the correct answer for a complete explanation.

C. This answer is incorrect. See the correct answer for a complete explanation.

D. If P represents the probability that the process is in control, then (1 - P) must represent the probability that the process is out of control. The problem tells us that the model is a two-state model. The process can be either in control or out of control, and there can't be any other probabilities. The sum of all probabilities is always equal to 1. Therefore, when P is the probability that the process is in control, (1 - P) must be the probability that it is out of control.