Select the correct answer from each drop-down menu. A group of doctors are conducting an experiment to test a new nutritional supplement. They randomly selected 600 subjects, assigning 300 subjects to receive the supplement and 300 subjects to receive a placebo. The doctors are unaware of which subjects are assigned to each treatment group.

This experiment is (Blinded/Not Blinded/Double Blinded) because (only the subjects/only the researchers/Neither researchers nor subjects) know which treatment group each subject is in.