Which of the following statements is not true?

A researcher is interested in whether a certain protein supplement increases muscle mass. The researcher obtains a sample of n = 100 participants and give each participant a certain amount of the protein supplment. After six months, the participants had their muscle mass measured. The mean muscle mass is equal to M = 73. For the general population, the muscle mass forms a normal distribution with mu equal to 55 and sigma equal to 25. Can the researcher conclude that the protein supplement significantly increased muscle mass at the 5% significance level? Which of the following is NOT true? A or = 0.05 B S = 19 C Ho: H = 55 D Ha: H > 55