Which of these was one of Aaron's sons chosen to serve as a priest?

Answer: Eleazar

God told Moses to bring his brother Aaron and Aaron's sons Nadab, Abihu, Eleazar and Ithamar to serve Him as priests.

““Next, have your brother Aaron brought to you from among the Israelites, along with his sons Nadab, Abihu, Eleazar, and Ithamar, to serve Me as priests.”— Exodus 28:1 (BSB)