A scientist wants to determine whether a new chemical she isolated can cure a certain disease. To test her hypothesis that the new chemical cures the disease more effectively than current treatments, she infects mice with the disease and gives them the new chemical. She then assesses how many mice were cured of the disease. What is missing from her experimental design?
A. She is missing a control group of mice that did not receive the new chemical.
B. She is missing an experimental group of mice that received a half dose of the new chemical.
C. She is not missing anything—her experimental design is adequate to test her hypothesis.
D. There are no variables in the experiment