Concept:Eid al-Adha is the Islamic festival of sacrifice that marks the climax of the Hajj pilgrimage.Explanation:The first ten days of Dhul-Hijjah are sacred in Islam.The ninth day of Dhul-Hijjah is the Day of Arafah, when pilgrims stand in prayer.Eid al-Adha is celebrated on the following day.Therefore, Eid al-Adha falls on the tenth day of Dhul-Hijjah.This makes option C the correct choice.Answer:C. Tenth