To construct a copy of ∠BAC using point D and the auxiliary segment, the correct next step for Saadiq is:
B. Saadiq needs to draw an arc through the sides of ∠BAC.
This involves placing the compass point at point A and drawing an arc that intersects both sides of the angle (i.e., lines AB and AC). This will allow Saadiq to transfer the angle's measurements to the new angle created at point D.