The correct option is C 11 hours 30 minutes
We know that the actual time difference between the early sunrise and actual sunrise is about 2 minutes due to atmospheric refraction. So we see actual sunrise at 6:00 AM i.e. two minutes after early sunrise.
Similarly man observe sunset at 5:32 PM but Sun is actually below the horizon, it appears at the horizon due to atmospheric refraction. Actual sunset is at 5:30 PM i.e. 2 minutes before delayed sunset.
Therefore, the length of the day between the actual sunrise (6:00 AM) and sunset (5:30 PM) is 11 hours 30 minutes.