What kinds of adverbs can modify "impossible"?

[roseriver1012]

Lang Lang is so brilliant a pianist that it's ________ impossible to go beyond him without hardwork.

A. very B. quite C. rather D. pretty
I have no clue about it! Impossible is an adjective, but why some adverbs can not be used to modify it? Can you give me some other examples of this kind? Thanks for your help!

[roseriver1012]

[Raymott]

"quite impossible" is the only answer.

[roseriver1012]

"quite impossible" is the only answer.

Why can't I use other adverbs before "impossible"?

[Raymott]

Why can't I use other adverbs before "impossible"?

If something's impossible, it's impossible.
You can say "almost impossible", but most others, we just don't say.