Skinfold thickness over the triceps muscle in the arm is an anthropometric measure that varies with states of health.Tablebelow lists skinfold measurement at the midpoint of the triceps in eight men with chronic lung disease and nine comparably aged controls.

Chronic lung disease:

9 11 11 15 25.4 13 21 18

Controls:

31 39 23 19 25 38 26 36 19

What is the sample standard deviation of the age control?

A.61.52

B.26

C.7.8

D.31.96