The correct answer is:
D. He invented a new branch of mathematics, algebra.
Explanation:
Al-Khwarizmi was a Muslim mathematician, astronomer and geographer, that is also known as the Father of Algebra, because he was the first to introduce letters to equations, as a sign of an unknown number to solve equations, and to treat Algebra as an independent science.
Al-Khwarizmi demonstrated the method to solve quadratic equations and proved the methods of reduction, <em>known in Arab as Al-Jabr</em> (the transposition of negative quantities to the other side of the equation to transform them into positive quantities) and balancing, <em>known in Arab as Al-Muqâbalah</em> (the elimination of identical quantities of both sides of the equation).