What must be proven regarding a defect in a products liability case under the theory of negligence?

In a products liability case under the theory of negligence, it is essential to establish that the defect in the product existed at the time it was sold. This is because negligence involves a duty of care that manufacturers owe to consumers, which includes the responsibility to ensure that their products are reasonably free from defects that could cause harm. If a defect arose after the product left the manufacturer's control—such as through misuse by a consumer or due to later wear and tear—then the manufacturer may not be held liable under negligence.

The focus on the condition of the product at the point of sale is crucial in proving negligence. It establishes a clear connection between the manufacturer’s actions (or lack thereof) and the harm suffered by the consumer. This principle reinforces the concept that manufacturers must ensure their products are safe when they enter the market, thus prioritizing consumer safety.

The other options focus on different aspects that are not essential for proving negligence in this context. For instance, while improper use might affect liability in certain scenarios, it does not negate the requirement to show that a defect was present upon sale. Similarly, knowledge of the defect by the manufacturer is a consideration for strict liability claims but not necessarily required under a negligence theory. Lastly, any damage caused by a consumer does