The paragraph below, about a spring-fed pool, is missing its Topic Sentence.
Of the four answers you have to choose from, select the one that serves as
the best Topic Sentence for this paragraph:
Whether in the heat of summer or
the cold of winter, the water temperature remains constant. In the winter,
when it's cold outside, the water actually feels warm when you first jump in.
During the summer, when the temperature outside is close to 100 degrees,
people often yelp when they get in because the water feels cold compared to
the hot air.
An endangered species of salamander lives in Barton Springs pool and is
protected by an environmental group based in Texas.
Austin, the capital of Texas, attracts thousands of visitors each year.
Many indoor swimming pools exist in the desert regions of Texas and
other areas of the West.
Barton Springs pool is a spring-fed swimming pool in Texas in which the
water is 68 degrees all year round.