Concept:Ziyarah is a recommended visit to the Prophet's Mosque in Madinah, not a compulsory rite of Hajj.
Explanation:Tawaf, ihram, and talbiyyah are all essential acts of Hajj performed in Makkah.
Tawaf is the circumambulation of the Kaaba seven times.
Ihram is the sacred state a pilgrim enters before starting the rites.
Talbiyyah is the chanted declaration of intention during the pilgrimage.
Ziyarah, however, refers to visiting Madinah and the Prophet's Mosque.
Although it is a praiseworthy act, it is not counted among the pillars or obligatory requirements of Hajj.
Since the question asks for the act that is not part of Hajj, ziyarah is the exception.
Answer:C. ziyarah