The underlined idiom in the following sentence means
People these days want to be rich overnight; naturally they try to earn money by hook or crook.

The correct answer is Option B (by fair or foul means).

Key Points:
• This question tests the meaning of the common English idiom 'by hook or crook'.
• Meaning of the Idiom:
• To achieve something *by hook or crook* means by any method possible, whether honest or dishonest, fair or foul.
• Evaluating options:
• Option 1: by legal or illegal ways (partially correct, but option 2 is the classic idiom definition).
• Option 2: by fair or foul means (Using any means, honest or dishonest, to achieve a goal).
• Therefore, Option 2 is the exact idiomatic meaning.
• Key Takeaway: The idiom 'by hook or crook' means achieving something by any means necessary, fair or foul.