Answer: Option C
Step-by-step explanation:
The tropical Diseases Such as Malaria and Yellow fever had to be eliminated before it was safe for workers to begin construction is the right answer.
The French also tried to build a Panama canal in 1880's but couldn't succeed due to the deaths of workers. When the United States took up the Panama project, Dr. William Gorgas was appointed as a chief sanitary officer. He was in charge of preventing yellow fever and malaria among the workers. Effective sanitation efforts were crucial for American success.