is the angle between the hour hand and the minute hand, when the time is 06:30. This is a/an angle.

The correct options are
B ${15}^{\circ }$
C acute

In one hour, the minute hand covers 360° and hour hand covers 30°.
When the minute hand covers 180°, hour hand covers 15°.
So at 6:30, minute hand covers 180° and hour hand covers 195°. The angle included between the minute and hour hand at 6:30 is 15°.