Final answer:
The term 'Aga Khan' comes from the Persian language and was granted to the leader of the Nizari Ismaili Muslims in the 19th century by the Shah of Persia.
Step-by-step explanation:
The term 'Aga Khan' originally comes from the Persian language. The title 'Aga Khan' was granted by the Shah of Persia in the 19th century to the leader of the Nizari Ismaili Muslims. This lineage of spiritual leaders has since used the title, which is hereditary. The Persian language has historically been influential in various regions, particularly in South Asia where it was often the language of government, literature, and high culture during different periods, such as the Safavid and Mughal eras.