If is a matrix satisfying , then the sum of the diagonal entries of is
The explanation for the correct option
Let us assume that, .
It is given that, .
Now,
Compare both sides of the equation.
Thus, , and .
Now,
Put the values , and .
Compare both sides of the equation.
Thus, , and .
Now,
Put the values , , , , and .
Compare both sides of the equation.
Thus, , and .
Therefore, the sum of the diagonal entries of can be given by, .
Hence, (A) is the correct option.