In order for a spark plug to work optimally the spark plug gap should be 0.2 inches. (If the gap is either too wide or too narrow, the spark plugs will not operate efficiently.) The quality control manager suspects that the manufacturing process is off and needs to berecalibrated. He decides to check by selecting a simple random sample of 41 spark plugs and finds the sample mean is 0.235 inches with a standard deviation of 0.08 inches. He wishes to determine whether recalibration is necessary.

A. Choose the best set to demonstrate the null and alternative hypotheses