The given polynomials are as ,
[tex]\begin{gathered} 2x^2+7x+6\text{ and} \\ 3x^2-x \end{gathered}[/tex]We have to subtracrt these given polynomials,
[tex]\begin{gathered} =2x^2+7x+6-3x^2-(-x) \\ =2x^2+7x+6-3x^2+x \\ =-3x^2+2x^2+7x+x+6 \\ =-x^2+8x+6 \end{gathered}[/tex]Option D is correct.