Final answer:
The value of k that will make the left side of the equation a perfect square trinomial is 30.
Step-by-step explanation:
In order for the left side of the equation to be a perfect square trinomial, the middle term in the trinomial must be twice the product of the square root of the first term and the square root of the last term.
In this case, the first term is 9x^2 and the last term is 25, so the middle term should be 2(sqrt(9x^2) * sqrt(25)) = 2(3x)(5) = 30x.
Therefore, the value of k that makes the left side a perfect square trinomial is 30. Therefore, the correct answer is D.