A Coach Uses a New Technique in Training Middle Distance

Multiple Choice

A coach uses a new technique in training middle distance runners.The times for 9 different athletes to run 800 metres before and after this training are shown below.
Construct a 99% confidence interval for the mean difference of the "before" minus "after" times if
(before - after) = 1.222 and
= 1.826

A) (-0.54,2.98)
B) (-6.42,8.87)
C) (-0.85,3.29)
D) (-0.76,3.20)
E) (-0.82,3.26)