Tuskegee syphilis, is it ethical or unethical explain

The Tuskegee syphilis experiment is considered unethical for many reasons. Syphilis is an STD that can cause deadly infections and heart problems. The subjects were African Americans from Alabama. They did not give consent from what is known and were not informed of the dangers. They had to agree to an autopsy to make money for their funeral. There was a cure at the time that they were not given, many people were denied treatment so scientists could observe the fatal progression of the disease. The people came in hopes of treatment, there was an advertisement with the slogan "Last Chance For Special Free Treatment", which was not true. The study ended in 1972, and a cure had been available for 25 years.
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Their solution was to tax the colonists. 

Correct answer for apex is d.