Final answer:
In an experiment for a new drug, different doses are being tested to determine the most effective one.
Step-by-step explanation:
In an experiment for a new drug to determine the most effective dose and medication, four different doses are being tested: 5 mg, 10 mg, 15 mg, and 20 mg. The goal is to understand which dose produces the best results in terms of effectiveness. This experiment is conducted in the field of medicine.