Have feet of clay means to have a hidden weakness despite an admirable image. The correct answer is this meaning because the expression is used figuratively, not only by its literal words.

Examples:

• The famous leader was later found to have feet of clay.
• In an HSC essay, Have feet of clay can express this meaning: to have a hidden weakness despite an admirable image.
• When this expression appears in a passage, connect Have feet of clay with the idea of to have a hidden weakness despite an admirable image.