To construct a copy of angle \( \angle BAC \) using the auxiliary segment where point D is placed, Saadiq should first replicate the angle's measure at point D.
Therefore, the correct step for Saadiq to take next is:
A. Saadiq needs to draw an arc on the auxiliary segment using point D.
This step involves placing the compass point at D and drawing an arc that intersects the lines that will eventually represent the rays of the angle, creating points for the angle's sides. After this, he can proceed with further steps to accurately replicate the angle.