Question

the passage below describes an experiment. erin grows peppers in her community garden. she read that nitrogen - rich soil allows plants to grow faster. so, erin prepared nine pots for her pepper plants. in three pots she added only top soil. in three other pots she added top soil and one - half cup of nitrogen - based fertilizer. in the remaining three pots she added top soil and one cup of nitrogen - based fertilizer. she planted one pepper seed in each pot and observed how long it took for each plant to bear fruit. in this experiment, the pots with top soil and one - half cup of fertilizer were part of ____ an experimental group a control group

Explanation:

In an experiment, the control group is the group that does not receive the experimental treatment, while experimental groups receive different levels of the treatment. Here, pots with only top - soil are the control group, and pots with different amounts of nitrogen - based fertilizer (including the ones with one - half cup) are experimental groups as they receive the treatment of added fertilizer to test the effect on plant growth.

Answer:

an experimental group