The key difference between closed-loop and open-loop payment systems is that:

The key difference between closed-loop and open-loop payment systems is that: a. a merchant bank is a required third party in open-loop payment systems whereas it is not needed in closed-loop payment systems. b. open-loop payment systems rely on blockchain technology whereas closed-loop payment systems do not rely on blockchain. C. closed-loop payment systems are for businesses whereas open-loop payment systems are for consumers. d. There are no major differences between closed-loop and open-loop payment systems