Ans: D
$\begin{array}{cl}
& 2\sin(90^\circ – \theta)\sin 60^\circ – \cos 0^\circ \cos\theta \\
= & 2\cos \theta \times \dfrac{\sqrt{3}}{2} – 1 \times \cos \theta \\
= & \sqrt{3} \cos \theta – \cos \theta \\
= & (\sqrt{3}-1) \cos \theta
\end{array}$
$\begin{array}{cl}
& 2\sin(90^\circ – \theta)\sin 60^\circ – \cos 0^\circ \cos\theta \\
= & 2\cos \theta \times \dfrac{\sqrt{3}}{2} – 1 \times \cos \theta \\
= & \sqrt{3} \cos \theta – \cos \theta \\
= & (\sqrt{3}-1) \cos \theta
\end{array}$
