An e-commerce site allows customers to order products, based on availability.

Customers fill out an online application form containing name, phone number, credit card information, and products they want to purchase, which is then submitted to the e-commerce management system. The system checks that the products are available, and the system verifies that the customer has an authentic credit card and satisfactory past record of purchases. If the products are available and the customer meets the required criteria, the system confirms to the customer that order placement is successful. Otherwise, the customer is informed that order placement failed.

a. Draw Level-0 Data Flow Diagram (DFD) of the e-commerce management system.
b. Draw Level-1 Data Flow Diagram (DFD) of the e-commerce management system.