I got this in my last exam, and came up with:

So I get

So then I could

to get

But the teacher didn't like it. "Wrong choice", she said; and put me a 1.

Her solution was

I've been thinking, but can't come up with anything else... and have no idea how to get to the teacher's solution.

By the way, I'm a highschool student, haven't started university yet.

Any help?