Context: People can use the engineering-design process to develop solutions to problems. One step in the process is testing if a potential solution meets the requirements of the design.
The passage below describes how the engineering-design process was used to test a solution to a problem. Read the passage. Then answer the question below.

People with diabetes sometimes take a medicine made from insulin. Insulin can be made by a special type of bacteria. Emmy was a bioengineer who wanted to increase the amount of insulin that the bacteria produced by 20%. She read that giving the bacteria more nutrients could affect the amount of insulin they produced. So, Emmy gave extra nutrients to some of the bacteria. Then, she measured how much insulin those bacteria produced compared to bacteria that did not get extra nutrients.
Figure: studying bacteria in a laboratory.
Which of the following could Emmy's test show?
A. whether different types of bacteria would need different nutrients to produce insulin
B. whether producing more insulin would help the bacteria grow faster
C. whether she added enough nutrients to help the bacteria produce 20% more insulin
Answer with the option's letter from the given choices directly.

C