Final answer:
The expression 3x + 15 can be rewritten as 3(x + 5).
Step-by-step explanation:
The expression 3x + 15 can be rewritten as a product of the greatest common factor (GCF) and a new sum. To find the GCF, we need to identify the highest common factor that divides both 3x and 15. In this case, the GCF is 3, so we can rewrite 3x + 15 as 3(x + 5). The correct option is A) 3(x + 5).