Question

how can we control for the possible effects of the stress of oral injection and the injected saline when evaluating the effects of treatment 3?
a) compare treatment 3 rabbits to rabbits injected orally with banana plus oil
b) compare treatment 3 rabbits to rabbits injected with estrogen with banana
c) compare treatment 3 rabbits to rabbits receiving no injection
d) compare treatment 3 rabbits to rabbits injected orally with banana plus physiological saline

Explanation:

Answer:

d) Compare treatment 3 rabbits to rabbits injected orally with banana plus physiological saline