A error occurs when the process mean is stable and in-control but an output result has occurred above the UCL or below the LCL. So, in this situation a false out-of-control signal has occurred.

The correct answer is letter "C": alpha.

Explanation:

In statistics, while talking about probabilities, an Error Type I or Alpha (α) Error takes place when a null hypothesis is rejected but these results to be true. In other words, the error happens when it is believed that the process is out of control when it really is under control. The probability of making an error Type I is α, which is the value a researcher gives for his hypothesis.

a is the correct answer, tell me if im right

answer; i believe the correct answer is (sales promotion;