Select the most appropriate idiom that can substitute the underlined words in the given sentence.
Sharon doing the work all by herself? Seems like it is possible, but is very unlikely to happen.

The phrase "possible, but very unlikely to happen" or an empty, unrealistic hope matches the meaning of the idiom "pie in the sky". It refers to an idea or plan that is pleasant to contemplate but very unlikely to be realized.
"Bent out of shape" means to become extremely angry or upset.

"A piece of cake" means something that is very easy to do.

"A bad egg" refers to someone who is dishonest or untrustworthy.