AP Psychology Practice Test 2026 - Free AP Psychology Practice Questions and Study Guide

A zygote is the correct answer because it refers to a fertilized egg, which is formed when a sperm cell fertilizes an egg cell during conception. This single cell contains all the genetic information needed to form a new individual. The other options are incorrect because:

- A mature embryo comes after the zygote stage, as the zygote undergoes cell division and differentiation to develop into an embryo.

- Cell division is a general process that occurs in the formation of the zygote but does not specifically define what a zygote is.

- A newborn human is the stage when the baby is born and is well past the zygote stage of development.