The correct answer is D.
The Supreme Court's decision in Plessy v. Ferguson was unconstitutional because it was not consistent with the 14th ammenment.
The 14th ammendment grants citizenship and equal civil and legal rights to African Americans and slaves who were emancipated after the American Civil War.
Segregation laws were explicitly againts the ammendment because they did not provide equal protection and liberties to non-whites. By forcing them to sit separated from white people, african-americans were being banned from fully excersing their rights.
The total runners who began the marathon is 1000
<u>Explanation:</u>
Given:
Runners who completed the marathon = 90%
Men = 30%
Number of men completed the marathon = 270
Total runners who began the marathon = ?
Let the total runners be x
According to question:
Runners who completed the marathon = 
= 0.9x
and,

Solving further:

Therefore, total runners who began the marathon is 1000