Correct Answer: To evaluate people’s worth by their outward appearance

Solution : The third option is correct.

Explanation: This idiom is a metaphorical expression that advises against forming opinions or making judgements about someone or something based solely on their outward appearance. It implies that one should not make assumptions about the true nature, character, or value of something or someone just by considering external features. In this context, the phrase judging a book by its cover is often used to caution against making hasty or superficial judgements.

Therefore, the correct answer is: " To evaluate people’s worth by their outward appearance".