Ans: D
$\begin{array}{cl}
& (4x+y)^2-(4x-y)^2 \\
= & (16x^2+8xy+y^2) – ( 16x^2-8xy+y^2) \\
= & 16x^2+8xy+y^2-16x^2+8xy-y^2 \\
= & 16xy
\end{array}$
$\begin{array}{cl}
& (4x+y)^2-(4x-y)^2 \\
= & (16x^2+8xy+y^2) – ( 16x^2-8xy+y^2) \\
= & 16x^2+8xy+y^2-16x^2+8xy-y^2 \\
= & 16xy
\end{array}$
