Section: Writing: Sentence Correction

59) Then he dropped them both, and the big one landed first--which he had thought it would do, and the little one landed second, which he had thought it would do.

1. one landed first—which
2. one landed first, which
3. one landed first: that
4. one landed first; which
5. one landed first—that

The punctuation should be the same for both of the parallel clauses.