Peachey explained the right answer already. I'll try to explain the other answer. This sounds like two people talking. "would you, really" doesn't fit because the first person said they would NOT do something. If they said they would do something then "would you, really?" could work. Here is an example of one way you might use sentence 1: Person 1 "I would jump off that bridge if I had a swimsuit on" Person 2 "Would you, really?". Person 2 is asking for confirmation from person 1, or you could say person 2 is checking to see if person 1 is serious about jumping off the bridge.

It's called an "echo question". Don't confuse it with a tag question. a: I wouldn't do that if I were you. b: Wouldn't you? Why? Echo questions need two speakers, and the auxiliary verb is repeated (not reversed to positive/negative). Tag questions need only one speaker.

My guess Because, "2" is the correct response for "a". So "1" should be the correct response for "b" And since "1" says "Would you, really!" logically "b" is going to be "I would do that if I were you." "affirmative, negative, conditional sentences"

I think 2 would be correct.

this is from english test university entrance exam 2014.