Identify the correct steps involved in proving that the matrix that represents the reflexive closure of a relation r on a finite set a is mr ? in, where mr is the matrix representing the relation r.
a) Replace all 0's in the main diagonal with 1's.
b) Replace all 1's in the main diagonal with 0's.
c) Add 1's to the elements of the main diagonal.
d) Add 0's to the elements of the main diagonal.