Ans: D
By comparing the graphs of $y=\sin x^\circ$ and $y=\sin(kx^\circ + \theta)$, we found that the graph of $y=\sin x^\circ$ is translated to the left $30^\circ$ and then reduced to $\dfrac{1}{2}$ times to obtain the graph of $y=\sin(kx^\circ + \theta)$. Hence, $k=2$ and $\theta =30^\circ$.
