Answer:
C
Step-by-step explanation:
Let's try it
Take 4 out of the given function.
4(x^2 + 3x )
Now there is an ex on either side of the plus sign that can come out. If 4 can come out because a 4 is on either side of the plus sign, so can an ex.
4x(x + 3)
What have you found?
4 is a factor
x is a factor
x + 3 is a factor
What about 3x. Well it won't work evenly and a factor must divide evenly into the given function.