California Assessment of Student Performance and Progress (CAASPP) Math Practice Exam 2026 - Free CAASPP Math Practice Questions and Study Guide

The first prime number is two, which is unique among prime numbers in that it is the only even prime. A prime number is defined as a natural number greater than one that has no positive divisors other than one and itself. In the case of two, its only divisors are one and two, meeting the criteria for being prime.

The other numbers listed do not fulfill the requirement of being the first prime. One is not considered a prime number because it does not meet the definition of having exactly two distinct positive divisors. Three and five, while both prime numbers, follow two in the sequence of prime numbers. Therefore, two is the correct and definitive answer as the first prime number in the sequence of natural numbers.