—How long do you think it will be________the Stock Market returns to normal?

—At least one year, I guess.

—How long do you think it will be___ the Stock Market returns to normal?

—At least one year, I guess.

1. A.
   before
2. B.
   when
3. C.
   until
4. D.
   that

—How long do you think it will be________the Stock Market returns to normal?
—At least one year, I guess.

—How long do you think it will be___ the Stock Market returns to normal?
—At least one year, I guess.