If a party voluntarily uses a product in an unreasonable manner, the seller will be relieved on liability on what defense?

Answer: Product Liability

Explanation:

Product Liability can be defined as the liability imposed on producers/makers and distributors of products, for injuries/harms caused to either of people or property, in some cases, both people and property by defective or products that caused unreasonably danger. Therefore, in this case, product liability will relieve the seller.