Answer: The correct answer is C.
Step-by-step explanation: If you factor the equation using the AC method, you will get this answer. Multiply A by C. For example, you would multiply 4 by 5 to get 20. List the factors of your answer from step two. That is, list pairs of numbers that you could multiply to come up with that answer. For instance, in the case of 20, you would have the following factors: (1, 20), (2, 10), (4, 5).
Find a pair of numbers among the factors that adds up to the B term in the equation. For this example, you must find a pair that adds up to 9. Therefore, you would isolate the pair (4, 5).
Replace the middle term (the B term) with the two numbers from the pair, along with the original variable that went with the B term. For example, you would write: 4x^2 + (4+5)x + 5 = 4x^2 + 4x + 5x + 5.
Group the first two terms and the last two terms together as such: (4x^2 + 4x) + (5x + 5).
Simplify the equation by finding terms that are common for each side. For instance, you would simplify (4x^2 + 4x) + (5x + 5) to 4x(x + 1) + 5 (x + 1). This would further simplify to (4x + 5) (x + 1).
