If the price of a product remains constant, what would be the firm's extra revenue from the sale of an additional unit of the product? Select a Choice Below current question choices OptionA The firm's extra revenue from the sale of an additional unit will be equal to the price of the product. OptionB The firm's extra revenue from the sale of an additional unit will be equal to the unit cost of the product. OptionC The firm's extra revenue from the sale of an additional unit will be equal to zero. OptionD The firm's extra revenue from the sale of an additional unit will be equal to the difference between the price and the unit cost of the product