The correct answer is (a).
The double possibility rule was laid down in the case of Whitby v. Mitchell (1890). The rule states that if a person is injured by the negligence of another, they can only recover damages if it is more likely than not that they would not have been injured if the negligence had not occurred.
In the case of Whitby v. Mitchell, the plaintiff was injured when he was hit by a train. He claimed that the train driver was negligent in failing to see him and stop the train. The defendant argued that the plaintiff would have been injured even if the train driver had not been negligent, because he was standing in the middle of the tracks.
The court held that the plaintiff could recover damages, because it was more likely than not that he would not have been injured if the train driver had not been negligent. The court found that the train driver had a duty to take reasonable care to avoid hitting people, and that he had breached that duty by failing to see the plaintiff and stop the train. The court also found that the plaintiff would not have been injured if the train driver had not been negligent, because he would have been able to get out of the way of the train if the train driver had stopped in time.
The double possibility rule is a common law rule that is applied in many jurisdictions. The rule is designed to protect defendants from liability for injuries that would have occurred even if they had not been negligent. The rule is also designed to ensure that plaintiffs only recover damages for injuries that are caused by the negligence of others.
The double possibility rule has been criticized by some legal scholars, who argue that it is too restrictive and that it does not adequately compensate plaintiffs for their injuries. However, the rule remains an important part of the law of negligence, and it is likely to continue to be applied in many jurisdictions.
The other options are incorrect because they do not refer to cases in which the double possibility rule was laid down.