Regina conducted an investigation to determine whether earthworms add nutrients to soil. She used two pots of soil. She added three earthworms to the first pot. She did not add any earthworms to the second pot, which was the control. Regina tested the nutrient levels of the soil in both pots after two weeks. What type of investigation is Regina conducting?

The question is incomplete, the complete question is:

Regina conducted an investigation to determine whether earthworms add nutrients to soil. She used two pots of soil. She added three earthworms to the first pot. She did not add any earthworms to the second pot, which was the control. Regina tested the nutrient levels of the soil in both pots after two weeks.

What type of investigation is Regina conducting?

descriptive

comparative

experimental

procedural

experimental

Explanation:

In an experimental study, there is an independent variable, a dependent variable and a set up meant for control.

The control is set up to establish the validity of the study.

Experiments are designed to establish cause and effect relationship. In this case, the experiment was designed to establish weather earthworms add nutrient to the soil.