At which of the times shown in the options, the hour hand and the minute hand of your clock will be perpendicular to each other?
09:00
03:45
At 09:00 and 03:00, hour hand and minute hand are at right angles to each other. Whereas at 6:15, we see that minute hand will be exactly at 3 but hour hand will not remain at 6. As it was at 6 when the minute hand was at 12. And since then, minute hand has moved (a quarter of round) which would cause hour hand to move too. So, the angle will not be 90∘ in that case.