Researchers Have Claimed That the Average Number of Headaches Per $H _ { 0 } : \mu = 10$

Researchers have claimed that the average number of headaches per student during a semester of Statistics is 10. Statistics students believe the average is higher. In a sample of n = 24 students the mean is 15 headaches with a deviation of 2. Which of the following represent the null and alternative hypotheses necessary to test the students' belief? A) $H _ { 0 } : \mu = 10$ vs. $H _ { \mathrm { a } } : \mu > 10$
B) $H _ { 0 } : \mu < 10$ vs. $H _ { \mathrm { a } } : \mu = 10$
C) $H _ { 0 } : \mu = 10$ vs. $H _ { a } : \mu < 10$
D) $H _ { 0 } : \mu = 10$ vs. $H _ { a } : \mu \neq 10$