The Figure Below Is from an Experiment on Athletes

Multiple Choice

The figure below is from an experiment on athletes. The "live high, train low" group lived for 18 days in rooms with a simulated altitude of 3,000 m, while training (exercising) at 1,200 m. Use this information and this figure to answer the following questions.
-The scientists studied 11 elite runners in this experiment. How does their sample size affect the validity of their study?

A) The small sample size limits how broadly their conclusions apply to athletes in general.
B) The sample size is sufficient to make conclusions about all endurance athletes, because there are very few endurance athletes.
C) Although the sample size was small, scientists should still consider these results as reliable as results from larger sample sizes because it is very hard to study humans.