Question

which is the best topic sentence for the second paragraph of an essay about \effects of exercise\?
in addition, a reason to turn off your lights is to save money on electricity.
in addition, if you brush your teeth twice a day you are less likely to get gum disease.
in addition, an effect of exercise is healthy skin.

Explanation:

The essay is about "effects of exercise". The first two options are off - topic. The third option is related to the effects of exercise, making it suitable as a topic sentence for the second paragraph.

Answer:

In addition, an effect of exercise is healthy skin.