The answer is the first three. The speaker has a unique imagination so the answer is going to be directed towards the speaker. The first, second, and third answer directly acknowledges how the author sees things differently than everyone else. The other or last two options say what everyone else can see and is therefor not contributing to his imagination.
No, a preposition is often used to describe where usually following a noun, such as in, on, with, by, and etc. "But" is a coordinating conjecture. Hope this helps.!
