A full-fledged member means a complete and officially recognized member. The correct answer is this meaning because the expression is used figuratively, not only by its literal words.

Examples:

• After six months of training, she became a full-fledged member of the club.
• In an HSC essay, A full-fledged member can express this meaning: a complete and officially recognized member.
• When this expression appears in a passage, connect A full-fledged member with the idea of a complete and officially recognized member.