A researcher tests whether the dosage level of some drug (low, high) causes significant differences in health. To do this, the researcher randomly assigns rat subjects to receive a low or high dosage of the drug and records health-related measures in both groups. The type of method described is .

The correct answer is - experimental.

Explanation:

In this procedure, a researcher tests the differences in health caused by the different levels of drug dosage on two different rat groups as subject one with a high dose and other with a low dose.

This type of method is known as an experimental method which is a scientific research method in which the researcher controls and manipulates one or more factors that than analyze by the collecting data by the change occur in variables.

Thus, the correct answer is - experimental.