test number 4 section 4 question number 25

test number 4 section 4 question number 25 indicates
Choice B is correct.
they the college board explains:
In f(x), factoring out the greatest common factor, 2x, yields
f(x) = 2x (x2 + 3x + 2).

however I do not find 2x to be a factor of X^3 +6X +4 because the 4 has no X associated with it. I did not get the answer as b either but c. Could you explain?

Thx John