Which sentence best describes the runner whose velocity-time graph is shown here?

The runner ran forward for 2 seconds, and then backward for 2 more seconds.

The runner ran forward for 4 seconds - slowly for the first 2 seconds, then faster for the last 2 seconds.

The runner ran forward for 4 seconds - fast for the first 2 seconds, then more slowly for the last 2 seconds.

The runner stood still for 2 seconds, then moved suddenly, and then stood still again for 2 more seconds.