Answer:
A. The payment to factors whose supply is perfectly inelastic.
Step-by-step explanation:
This means that this factor of production need to be purchase regardless of the price change, otherwise the business operation couldn't continue.
One example of a pure economic rent is the cost of latex for rubber glove manufacturer. Since latex is the main ingredients for the product, that company still have to buy it even if the price of the latex is increasing (inelastic) . Otherwise, the company need to shut down its operation.