A Survey of Full Professors (Highest Ranking) in History Found

A survey of full professors (highest ranking) in History found that the average income is $74,914. Because that survey is now over 8 years old, an institutional researcher wants to test this figure by taking a random sample of 112 History professors with full professorship status. The researcher finds a sample mean of $81,342. The population standard deviation is known to be $15,121.
-The null and alternative hypotheses to determine is the figure has changed is _____.

A) H₀: µ = 74,914 H_a: µ ≠ 74,914
B) H₀: µ ≥ 74,914 H_a: µ < 74,914
C) H₀: µ ≤ 74,914 H_a: µ > 74,914
D) H₀: µ ≠ 74,914 H_a: µ = 74,914
E) H₀: µ ≤ 81,342 H_a: µ > 81,342