What's the answer to this question?

The correct answer is A!!

Explanation:

Fewer workers got sick from malaria and yellow fever.A canal in Central America would make it easier to reach the Pacific Ocean from the eastern coast of the United States.New scientific knowledge help the building of the Panama canal because there was a decrease of workers getting sick of malaria and yellow fever. It was Colonel Gorgas, the Chief Medical Officer, who have read about discoveries linking mosquitoes and malaria. Due to these readings, he succeed in eradicating the cause of the disease therefore a decrease in people getting sick.

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