Use the grouping method to factor this polynomial completely.
4x^3 + 8x^2 + 3x + 6
A. (4x^2 + 2)(x+3)
B. (4x^2 + 3)(x+2)
C. (4x^2 + 2)(x+ 2)
D. (4x^2 + 3)(x + 3)