Which of these factors is the most important for achieving good physical fitness? a. behavior b. gender c. environment d. heredity select the best answer from the choices provided. a b c d

The answer would be A, behavior. In terms of good physical health, we can control our behavior by practicing a healthy lifestyle. 
People of both genders can be healthy so gender is eliminated. People can practice good health in almost any environment so that choice is eliminated. The last choice is eliminated because positive measures towards physical health can be made by all people regardless of genetics. 

Hope this helps! :)