When Focusing a Camera with Auto Iris, Focus Will Be

When focusing a camera with auto iris, focus will be more accurate if

A) Set during lowlight conditions, since the depth of field is shorter with a large iris opening.
B) Set during bright conditions, since the depth of field is shorter with a small iris opening.
C) Set during lowlight conditions, since the automatic gain control will increase image contrast.
D) Set during bright conditions, since image contrast will not be reduced by the automatic gain control.