Question

air pollution essay
persuasive essay outline
introduction
thesis statement:
air pollution is a problem because it can cause lung cancer, heart disease, and other adverse responses the lung health of teens.
body paragraph 1
topic sentence:
firstly, air pollution can cause lung cancer after exposure for long periods of time.
...
body paragraph 3
topic sentence
conclusion

choose the correct answer
which should be used for the topic sentence of body paragraph 3?
thirdly, air pollution can cause asthma after exposure for long periods of time.
water is made of hydrogen and oxygen atoms.
in space, oxygen must be provided to astronauts in order for them to survive.

Explanation:

The essay is about air pollution, so the topic sentence for Body Paragraph 3 should relate to air pollution's effects. The first option ("Thirdly, air pollution can cause asthma after exposure for long periods of time") is relevant to air pollution, while the other two options (about water composition and space oxygen) are off - topic.

Answer:

Thirdly, air pollution can cause asthma after exposure for long periods of time