Correct option is B
An acute angle is an angle that is less than 90°. To find when the minute and hour hands make an acute angle, we need to calculate the angle between the two hands at each time and check if it's acute (less than 90°).
Formula for the angle between the hour and minute hands:

Where H is the hour and M is the minutes.
Let's evaluate
At 6:30:

At 6:30, the angle between the hour and minute hands is 15°, which is an acute angle.