Clara Louis Maass was a only female person who contributed herself to the research on yellow fever. She was a civilian nurse in Cuba, where the experiments was conducted.
Two Army Majors, William Gorgas and Walter Reed were the leader of these experiments. They were trying to isolate the cause of the disease. They believed dirt and poor sanitation were causes of yellow fever, and a mosquito was the suspected carrier.
Clara volunteered herself to participate in the experiment. And she was in the group who would be bitten by the insect. She contracted the disease and died on August 24, 1901 along with a small number of other volunteers who died from it. With her death, the study ended; the result of the experiment provided conclusive evidence that mosquitoes were the source of the disease.
It can be inferred from the passage that many of the volunteers __________.
were not men
did not die
were not bitten by the insect
did not participate in the experiment