Which of the following could constitute contributory negligence per se?

Contributory negligence per se is established when a plaintiff violates a statute or ordinance that is designed to protect a specific class of individuals, resulting in harm that the statute aimed to prevent. In this context, a plaintiff's violation of a relevant statute would mean that the plaintiff failed to adhere to a legal rule intended to promote safety or prevent harm. This violation can directly contribute to the circumstances surrounding the injury, thereby establishing contributory negligence per se.

The law generally infers that when individuals do not follow regulations intended to protect them, they are contributing to their own harm. This legal concept allows a court to find the plaintiff partially or fully responsible for their injuries, regardless of the defendant's actions, based on the idea that adherence to the statute could have prevented the harm.

In contrast, the other options do not meet the criteria for contributory negligence per se. Compliance with regulations by the defendant shows that they acted appropriately, and the absence of a witness or lack of safety measures does not imply that the plaintiff contributed to their injury by violating a specific legal duty. Only the violation of a statute specifically relevant to the plaintiff's protection creates the basis for contributory negligence per se.