A change of tack means a change in method, plan, or direction. The correct answer is this meaning because the expression is used figuratively, not only by its literal words.

Examples:

• After the first plan failed, the team made a change of tack.
• In an HSC essay, A change of tack can express this meaning: a change in method, plan, or direction.
• When this expression appears in a passage, connect A change of tack with the idea of a change in method, plan, or direction.