The correct answer is (a) Ithana Ashari.
The four main Sunni schools of law are Hanafi, Maliki, Shafi’i, and Hanbali. Ithana Ashari is a school of Islamic theology, not law.
The Hanafi school is the oldest of the four Sunni schools of law. It was founded by Abu Hanifa in Kufa, Iraq, in the 8th century. The Hanafi school is the most widely followed school of law in the Sunni world, with about 40% of Sunni Muslims following it.
The Maliki school was founded by Malik ibn Anas in Medina, Saudi Arabia, in the 8th century. The Maliki school is the second most widely followed school of law in the Sunni world, with about 20% of Sunni Muslims following it.
The Shafi’i school was founded by Muhammad ibn Idris al-Shafi’i in Mecca, Saudi Arabia, in the 9th century. The Shafi’i school is the third most widely followed school of law in the Sunni world, with about 15% of Sunni Muslims following it.
The Hanbali school was founded by Ahmad ibn Hanbal in Baghdad, Iraq, in the 9th century. The Hanbali school is the fourth most widely followed school of law in the Sunni world, with about 15% of Sunni Muslims following it.
Ithana Ashari is a school of Islamic theology that was founded by Abu al-Hasan al-Ash’ari in Basra, Iraq, in the 9th century. The Ithana Ashari school is the most widely followed school of theology in the Sunni world.