Question

in a recent experiment, anti - bacterial hand sanitizer was compared to hand soap. students washed their hands using sanitizer or soap and warm water for two minutes, then, they dried their hands with a paper towel. the standard of comparison was rubbing hands vigorously for 2 minutes in warm water, without any soap or sanitizer, and then drying with a paper towel. the sanitizer advertisement claimed to kill bacteria more effectively than any soap. after washing, hands were swabbed, and then the swab was applied to a culture plate and incubated. finally, the bacterial cultures were counted. students using the antibacterial sanitizer had the lowest bacterial culture count. what is the control group in the experiment? a washing with soap b using soap or sanitizer c the time: two minutes d rubbing hands in warm water

Explanation:

In an experiment, the control group is the one without the variable (soap/sanitizer here). Option D (rubbing hands in warm water) has no soap/sanitizer, serving as the baseline to compare the effects of soap/sanitizer.

Answer:

D. rubbing hands in warm water