Concept:The Day of Arafah is the most important day of Hajj and falls on a specific date in Dhul-Hijjah.
Explanation:Pilgrims leave Mina and proceed to the plain of Arafah on the morning of the 9th day of Dhul-Hijjah.
At Arafah, they combine Dhuhr and Asr prayers and engage in intense supplication until sunset.
The Prophet Muhammad (SAW) said that Hajj is Arafah, meaning standing at Arafah is the core ritual.
After sunset, pilgrims move to Muzdalifah, so the day of standing is definitely the ninth day.
Therefore, the option that matches the correct date is the ninth day of Dhul-Hijjah.
Answer:D. ninth