The principal of a middle school claims that the mean age of the seventh-graders at his school is less than 14 years. Use α = 0.05 to test his claim. The summary statistics are
n = 30, overbar(x) = 12.6 years, s = 2.5 years. Assume that the population has a normal distribution.
Find the Test Statistic TS (without the absolute value).

A. 2.537
B. 5.241
C. -3.067
D. -16.8