Answer:
C. decrease the amount of weight until she can do five reps
.
Step-by-step explanation:
There are three things we can work on when it comes to muscles: muscle mass, muscle endurance and muscle strength.
In order to increase muscle mass, it is recommended to lift heavier weights with lower repetitions while muscle endurance is built by lighter weights and higher repetitions.
Muscle strength on the other hand is determined by the maximum amount of weight one can lift. In order to develop more muscular strength, Shawna should look for the maximum amount of weight she can lift five times. This is important because she must be able to endure at least two series of repetitions in order to work her strength properly.