A Randomized Experiment Was Done by Randomly Assigning Each Participant

A randomized experiment was done by randomly assigning each participant either to walk for half an hour three times a week or to sit quietly reading a book for half an hour three times a week. At the end of a year the change in participants' blood pressure over the year was measured, and the change was compared for the two groups.
-The two treatments in this study were

A) walking for half an hour three times a week and reading a book for half an hour three times a week.
B) having blood pressure measured at the beginning of the study and having blood pressure measured at the end of the study.
C) walking or reading a book for half an hour three times a week and having blood pressure measured.
D) walking or reading a book for half an hour three times a week and doing nothing.