Select the topic sentence in each of the following groups of jumbled paragraph sentences.(Hint: The topic sentence will have a main idea that all the remaining body sentences support.)

Four-time Olympic medalist swimmer Penny Oleksiak trains an average of 55 hours a week both in the pool and at the gym during racing season. 

In one of their tougher workouts, swimmers have to pull themselves out of the pool, do 20 pushups, and then dive back in to swim sprints.

Competitive swimmers must endure multiple daily pool workouts and weight training in order to improve their performance.

 

Swimmers also do strenuous workouts with a kickboard to build their speed.

 

In addition to time spent in the water, competitive swimmers must also lift weights to build their stamina.