When he returned he was accompanied by a sprightly young girl.

Answer: Option C

Sportive : playful; light-hearted.
Intelligent : having or showing intelligence, especially of a high level.
Lively : full of life and energy; active and outgoing.
Beautiful : pleasing the senses or mind aesthetically.
Sprightly : (especially of an old person) lively; full of energy.

Synonym of Sprightly is Lively