<u>Given</u>:
The given expression is 
We need to determine the values for which the domain is restricted.
<u>Restricted values:</u>
Let us determine the values restricted from the domain.
To determine the restricted values from the domain, let us set the denominator the function not equal to zero.
Thus, we have;

Taking square root on both sides, we get;



Thus, the restricted value from the domain is
Hence, Option A is the correct answer.
The three leaders are -
Harriet Tubman - Booker T. Washington - Martin Luther King JR
Reason is that unlike the others they led their fight against racism and discrimination.