He behaved so recklessly, so he would be disqualified from keeping his last job.

A Had he not behaved so recklessly, he wouldn’t have been fired from his last job.

B Without his reckless behavior, he would have lost his last job.

C If he hadn’t behaved so recklessly, he hadn’t quit his last job.

D He didn’t quit his job because he knew that he had behaved so recklessly.