Final answer:
The value 'c' that makes the expression x^2 + 2x + c a perfect square trinomial is 1, as it is the square of half the coefficient of 'x'. The correct option is C.
Step-by-step explanation:
The question asks which value 'c' makes the expression x^2 + 2x + c a perfect square trinomial. To form a perfect square trinomial from x^2 + 2x + c, we need to find a value of 'c' that is the square of half the coefficient of 'x'.
In the expression x^2 + 2x + c, the coefficient of 'x' is 2. Half of this coefficient is 1 (2 divided by 2), and the square of 1 is 1. Therefore, the value of 'c' that makes the expression a perfect square trinomial is 1, which corresponds to option C.