A scientist wishes to test a new antibiotic’s ability to treat stubborn bacterial infections. He tests his hypothesis that the antibiotic works better than existing treatments by giving bacterial infections to mice and treating them with the antibiotic. He then determines how many of the mice recover from their infections. What is missing from his experimental design?
a. He is missing a control group of mice that did not receive the new antibiotic.
b. Nothing is missing—he has done everything he needs to do for this to be a successful experiment.
c. There are no variables in the experiment
d. He is missing an experimental group of mice that received a half dose of the new antibiotic.