Ans - option c.
because the largest equivalence relation will be when every element is related to other element so, n * n = n^2 possible ordered pair.
since each pair is related to one another for example {a1} = {a1,a2,a3} , {a2} = {a1,a2,a3} , {a3} = {a1,a2,a3}
rank means number of equivalence classes in this case it is 1, hence rank is 1
{n^2,1} is the correct answer.