Final answer:
The correct factorization of the polynomial expression x^2+6x+9 is (x+3)(x+3), which is option (C).
Step-by-step explanation:
The correct factorization of the polynomial expression x^2+6x+9 is (x+3)(x+3), which is option (C). To factorize a quadratic trinomial like this, we look for two binomials that multiply together to give us the original expression. In this case, we can see that (x+3)(x+3) satisfies this condition. When we expand (x+3)(x+3), we get x^2+6x+9, which is the original expression.