What was Euclid’s contribution to mathematics that’s still in use today?(1 point)

The correct answer is **his textbook The Elements**.

**Why:** Euclid's "Elements" is a foundational text in mathematics, especially in the field of geometry. It systematically presented the principles of geometry through definitions, axioms, propositions, and proofs. The methods of logical reasoning and rigorous proof established in "The Elements" have greatly influenced mathematics and the way mathematical arguments are structured. Today, it is still referenced and utilized in mathematical education and serves as the basis for many of the principles taught in geometry courses.