Kelly was in a passenger plane that had engine trouble. she watched as all four engines quit, one at a time. then the plane exploded and she was thrown 5,000 feet in the air. it was a miracle that she survived, although she was severely injured. she landed in a thick pine forest covered with 10 feet or more of snow. when she regained consciousness several weeks later, she had a stress reaction that lasted for years, and she could never fly again. the factor that probably most contributed to her extreme posttraumatic stress reaction was: