Plaintiff was a passenger in a car that was struck in the rear by a car driven by First. The collision resulted from First's negligence in failing to keep a proper lookout. Plaintiff's physician found that the collision had aggravated a mild osteoarthritic condition in her lower back and had brought on similar, but new, symptoms in her neck and upper back. Six months after the first accident, Plaintiff was a passenger in a car that was struck in the rear by a car driven by Second. The collision resulted from Second's negligence in failing to keep a proper lookout. Plaintiff's physician found that the second collision had caused a general worsening of Plaintiff's condition, marked by a significant restriction of movement and muscle spasms in her back and neck. The physician believes Plaintiff's worsened condition is permanent, and he can find no basis for apportioning responsibility for her present worsened condition between the two automobile collisions. Plaintiff brought an action for damages against First and Second. At the close of Plaintiff's evidence, as outlined above, each of the defendants moved for a directed verdict in his favor on the ground that Plaintiff had failed to produce evidence on which the jury could determine how much damage each defendant had caused. The jurisdiction adheres to the common-law rules regarding joint and several liability. Plaintiff's best argument in opposition to the defendants' motions would be that the defendants are jointly and severally liable for Plaintiff's entire harm, because 
the wrongdoers, rather than their victim, should bear the burden of the impossibility of apportionment.  the defendants breached a common duty that each of them owed to Plaintiff. each of the defendants was the proximate cause in fact of all of Plaintiff's damages. the defendants are joint tortfeasors who aggravated Plaintiff's preexisting condition.