A doctor wants to determine if a new medication for cholesterol is more effective than the previous medication. The doctor informed his patients of the new medication and asked them if they would like to participate in a drug trial to test the effectiveness of the new cholesterol medicine compared to the current medication. Twenty-five patients who were currently taking medication for cholesterol volunteered and were given the new medication. After two months, the patients’ cholesterol levels are checked. Which of the following is a true statement about the design of this experiment?

This experiment will show the effectiveness of the new cholesterol medicine.

Because a random sample was not used, the doctor will not be able to determine the effectiveness of the new medicine.

Because the doctor did not have a different random sample of patients take the original medication, the effectiveness of the new medicine will not be able to be determined.

Because the doctor did not have a different random sample of patients not take any medication, the effectiveness of the new cholesterol medication will not be able to be determined.