The best way to cool down from a workout is to a. stop the activity immediately b. switch to a different workout activity c. continue the activity at a lower intensity d. take a cool shower

The correct answer here is C. continue the activity at a lower intensity.\

It's can't be the first choice (a) because immediately stopping after working out isn't healthy and it may cause you to feel soreness. 

It also can't be choice (b) because switching to a different workout isn't cooling down.

And finally, it can't be (d) because although you're temperature is physically becoming cooler, it doesn't mean that your muscles are. 

Stretching, walking, or slowing down your activity is considered a cool down.