Michael Taylor came up ___ the idea of walking around the world after a trekking holiday in the Himalaya.

• A. With
• B. For
• C. At
• D. In

Answer: (A)

Think of the phrasal verb come up with, which means to think of or produce an idea. In this sentence, Michael Taylor conceived the idea of walking around the world, so the natural form is “came up with the idea.” The word that fits is with, because the idiom is came up with, a single unit that links to the object the idea. The other prepositions don’t form this common idiom with the verb in this context, so they wouldn’t sound natural here.