Question

Muslims in several of Nigeria’s states have voted to adopt the _____.

Answer 1

I would say it's the "Islamic law called Shariah" since it's Nigeria's Muslim population. 

Answer 2

Answer:

Muslims in several of Nigeria's states have voted to adopt the Islamic law called Shariah.

Explanation:

In Islam, the Shariah is a concept that can be interpreted in a metaphysical or pragmatic way. In the metaphysical meaning, shariah is the Law of God and, as such, remains unknown to men.  In the pragmatic one, it represents the concrete effort exercised to identify the Law of God.

It has been formally instituted as a law by certain states, such as Iran, and Saudi Arabia, which are defined as an Islamic state. In those cases, the courts of justice are instituted as an Islamic court and ensure compliance. Many countries in the Islamic world, like Nigeria, although they have not been fully defined as an Islamic State, have partially adopted in their legislation elements of the Shariah.