During the course of successful prenatal development, a human organism begins as a(n) and ends up as a(n)

The correct answers are zygote and fetus. This is correct because the initial joining of the sperm and the egg is called the zygote. The zygote is the first step in prenatal development that grows and transforms over months into the final form, a fetus. The fetus is the last form of the zygote prior to birth.