Researchers Are Conducting a Study to Determine the Effects of Vitamin

Multiple Choice

Researchers are conducting a study to determine the effects of vitamin C on the human immune system.The study involves providing pills that contain vitamin C to one group of human subjects,and pills that do not contain vitamin C or other active ingredients to another group of people.The pills that do not contain the vitamin are

A) antidotes.
B) supplements.
C) placebos.
D) probiotics.