Answer:
Matched pairs design
Step-by-step explanation:
Looking at the options;
-It's not a completely randomized design because a randomized design will assign all individuals to a group which in this case it doesn't.
- It's not a randomized block design because randomized block design will group the subjects in question into 2 or more blocks which have a common characteristic and will then randomly assign subjects in each of the blocks.
-It's a matched pair because every individual/subject undergoes measurements both before and after being treated with the drugs.
Thus, the correct option is matched pairs design.