To determine the effect of beta-blockers on the pulse rate during surgery, 60 available subjects were randomly divided into two equal groups. One group received a beta-blocker; the other, a placebo. The pulse rate of each patient at a critical point during the operation was recorded. What test would you perform to answer the question: Do beta-blockers reduce the pulse rate during surgery? O z-test for individual means matched pairs t-test t-test for individual means two sample t-test