Choose the correct null and alternative hypothesis for the following situation: A simple random sample of 50 speeds (in mph) is obtained from cars traveling on a section of I-10 through Tallahassee. The sample has a mean of 72.3 mph and a standard deviation of 7.4 mph. Use a 0.05 significance level to test the claim that the mean speed of all cars is greater than the posted speed limit of 70 mph. Choose A, B, C, or D.