To estimate the average weight gain of pigs fed two different diets, nine pairs of pigs were used. The pigs in each pair were littermates. A coin toss was used to decide which pig in each pair got Diet A and which got Diet B. Select the appropriate inference procedure.

A. Two sample interval for 1−2

B. Two sample interval for 1−2

C. Two-sample test

D. Paired test

E. One sample interval for diff