–4x + 6x2 + 5x

A. 7x3
B. 6x2 + 9x
C. 6x2 – 9x
D. 6x2 + x

To combine like terms in this expression, we add or subtract the coefficients of x raised to the same power. In this case, the only like terms are the terms with x raised to the power of 2.

-4x + 6x^2 + 5x = 6x^2 - 4x + 5x

= 6x^2 + x

Therefore, the answer is D. 6x^2 + x.