Q: In this task, you are given a question and a context passage. You have to answer the question based on the given passage.
What led to the Sultan giving up sovereignty over Kenya?, Context: The first direct elections for native Kenyans to the Legislative Council took place in 1957. Despite British hopes of handing power to "moderate" local rivals, it was the Kenya African National Union (KANU) of Jomo Kenyatta that formed a government. The Colony of Kenya and the Protectorate of Kenya each came to an end on 12 December 1963 with independence being conferred on all of Kenya. The United Kingdom ceded sovereignty over the Colony of Kenya and, under an agreement dated 8 October 1963, the Sultan of Zanzibar agreed that simultaneous with independence for the Colony of Kenya, the Sultan would cease to have sovereignty over the Protectorate of Kenya so that all of Kenya would be one sovereign, independent state. In this way, Kenya became an independent country under the Kenya Independence Act 1963 of the United Kingdom. Exactly 12 months later on 12 December 1964, Kenya became a republic under the name "Republic of Kenya".
A:
an agreement dated 8 October 1963