The key personal decisions that can influence your personal safety while exercising are
a. making sure to replace lost fluids before, during, and after exercise
b. preparing for exercise in extreme temperatures
c. choosing when, where, and how to exercise
d. all of the above

The answer is letter D.

All of the choices given are preventive measures of exercising. A person who is engaging in an exercise activity is always exposed to different risks like injuries and accidents. In order to enjoy a fun and safe physical activity a person should always make sure that all the external stimuli (e.g. weather, hydration) are ready and suited for the type of activity to be performed. Dehydration is one of the most overlooked aspects of exercise. Individuals tend to forget to hydrate their body after sweating which leads to hyperthermia or heat stroke.

Hair follicles, blood, etc.

Yes you do , which is cool