Question

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

Explanation:

Regina has a control group (second pot without earthworms) and an experimental group (first pot with earthworms). She manipulates the presence of earthworms (independent variable) and measures nutrient levels (dependent variable). This setup is characteristic of an experimental investigation. A descriptive investigation just describes a phenomenon without manipulation. A comparative investigation compares different pre - existing groups without control over variables. A procedural investigation focuses on following a set of procedures rather than testing a hypothesis with variables.

Answer:

experimental