Which young woman was brought to care for the aged King David?

Answer: Abishag the Shunammite

They searched Israel for a beautiful girl and found Abishag the Shunammite, who cared for the king and served him.

“Then they searched throughout Israel for a beautiful girl, and they found Abishag the Shunammite and brought her to the king.”— 1 Kings 1:3 (BSB)