Eid al-Adha, also known as the "Festival of Sacrifice," is observed on the tenth day of the Islamic month of Dhul-Hijjah. This is a significant time in the Islamic calendar as Muslims worldwide commemorate the willingness of Prophet Ibrahim (Abraham) to sacrifice his son as an act of obedience to God. Before the sacrifice was carried out, God provided a ram to sacrifice instead, symbolizing divine intervention and mercy.
Eid al-Adha coincides with the completion of the pilgrimage rites by millions of Muslims in Mecca, known as Hajj, which also occurs in this holy month. The first ten days of Dhul-Hijjah are particularly important, culminating in Eid al-Adha on the tenth day. Therefore, the correct answer to when Eid al-Adha is observed is the tenth day of Dhul-Hijjah.