Which of the following is equivalent to the polynomial below

For this case what you must do is find the roots of the corresponding polynomial by means of a factorization.
 We have then:
 x ^ 2-10x + 61
 (x- (5 + 6i)) (x- (5-6i))
 Checking:
 (x- (5 + 6i)) (x- (5-6i))
 x ^ 2 - x * (5-6i) - (5 + 6i) x + (5 + 6i) * (5-6i)
 x ^ 2 - 5x + 6ix - 5x- 6ix + 25 - 30i + 30i + 36
 x ^ 2 -10x + 61
 
 (x- (5 + 6i)) (x- (5-6i))