A college football coach wondered whether the seniors on the team were complacent in their conditioning, so he randomly selected 20 seniors and paired each one with a randomly selected underclassmen who played the same position. Then he tested the time it took each of them to run a 40-yard dash. The results are given below (in seconds). Assume that the populations are normally distributed. The coach tests the paired data, where =0.05, in order to evaluate the claim that the true mean difference between a senior's 40-yard dash time and an underclassman's 40-yard dash time is greater than zero. (a) Which answer choice shows the correct null and alternative hypotheses for this test