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 who conducted this experiment were testing the hypothesis that living at high altitudes will boost red blood cell production, which can then affect stamina when training and competing at lower altitudes. What group of athletes is an appropriate control treatment for this experiment?

A) Athletes who lived and trained at 1,200 m.
B) Athletes who lived at 1,200 m and trained at 3,000 m.
C) Athletes who lived at 3,000 m and trained at 1,200 m.
D) Athletes who lived and trained at 3,000 m.