Answer : 2. "Euclid"
Explanation :

Euclid, a Greek mathematician who lived around 300 BCE, is often referred to as the "Father of Geometry." He is best known for his work "Elements," a comprehensive compilation of knowledge in mathematics at that time. In "Elements," Euclid presented a systematic and organized approach to geometry, including definitions, postulates, and theorems. His contributions laid the foundation for much of classical geometry, and his work became the standard textbook for teaching mathematics for many centuries. Euclid's influence on the development of geometry and mathematics, in general, earned him the title "Father of Geometry."