Uthman b. Affan was a prominent companion of the Prophet Muhammad (SAW) and the third caliph of the Islamic Ummah. He was born into the Banu Umayyah clan of the Quraysh tribe in Mecca, which was a powerful and influential family in pre-Islamic Arabia.
The Banu Umayyah were known for their wealth and status, and they held a prominent position in the affairs of Mecca. Uthman himself was known for his wealth and generosity, and he played a significant role in the early development of Islam. He was one of the first Muslims to migrate to Medina, and he was known for his close relationship with the Prophet Muhammad (SAW).
Therefore, the correct answer to the question is that Uthman b. Affan was born into the family of Banu Umayyah, and not Banu Quraysh, Banu Sa'd, or Banu Qaynuqah.