The reduction in cholesterol level after eating a certain brand of oatmeal for breakfast for one month in people with cholesterol levels over 200 is Normally distributed, with mean (in milligrams) μ and standard deviation σ = 8 . Although the brand advertises that eating their oatmeal for breakfast daily for one month will produce a mean decrease in cholesterol of more than 20 points for people with cholesterol levels over 200, you believe that the mean decrease in cholesterol is actually less than advertised. To explore this, you test the hypotheses H0 : μ = 20 , H a : μ < 20 at the 0.05 level. You will randomly select 144 people with cholesterol levels over 200. After they eat this brand of oatmeal for one month, you will compute the mean decrease in cholesterol levels of the subjects.

If you observe a sample mean cholesterol reduction of ¯x = 18.52 , the P ‑value obtained is:

A. less than 0.01.
B. between 0.025 and 0.5.
C. between 0.05 and 0.1.
D. between 0.01 and 0.025.