In the context of designing control charts, which of the following is true of a sample size? a. A large sample allows small changes in process characteristics to be detected with higher probability than a small sample size. b. A small sample is used to detect process shifts of two standard deviations or smaller. c. A large sample size is desirable to keep the cost associated with sampling low. d. A small sample size provides greater degrees of statistical accuracy in estimating the true state of control than a large sample size.