Which of the following is not a ritual of the hajj?

a. pilgrims undergo a ritual cleansing and put on special white garments
b."standing" on mount arafat for hours, praying at a place where muhammad held his last sermon.
c. three-day ritual of "stoning," in which they throw pebbles at three pillars.
d. four-day walking journey from mecca to medina while reading from the qur'an.

d.Four-day walking journey from Mecca to Medina while reading from the Qur'an.

Explanation:

From the above given options all of the actions are involved in the ritual of Hajj which Muslims have to perform once in their lifetime if they fall under the criteria of performing the Hajj.

They do undergo cleansing and wear white clothes.

They do stand on Mount Arafat for hours praying at the place where Muhammad (PBUH) held his last sermon.

They also definitely do the ritual of Stoning for the three consecutive days. BUT they do not go on a four day walking from Mecca to Medina reading the Holy Qur'an.