Final answer:
The control group in the experiment studying the effect of caffeine on the heartbeat of puppies is Litter B, which did not receive caffeine. This group serves as a baseline for comparison to determine the specific effects of caffeine on the heartbeat of Litter A.Therefore, the correct option is b) Litter B.
Step-by-step explanation:
In the experiment designed to study the effect of caffeine on the heartbeat of puppies, the control group is the group that would not receive the experimental treatment, which in this case is caffeine.
Litter B serves as the baseline to which the experimental group (Litter A) is compared. By not receiving caffeine, Litter B's heartbeat serves as a reference for the normal heartbeat rate of puppies of that age, gender, and size without the influence of the stimulant. This allows researchers to observe any differences in heart rate that are specifically due to the administration of caffeine to Litter A.
Control groups are a fundamental component of an experiment because they allow scientists to isolate the effect of the variable being tested, which is the presence of caffeine in this experiment. Any changes in the heartbeat of Litter A can be attributed to caffeine only if Litter B remains unaffected. Thus, maintaining similar conditions for both litters, except for the caffeine treatment, is essential for the validity of the experimental results.