Read the following case and answer the questions. Runner, the famous toy company has been experiencing decline sales for the last two seasons. This company designs and sells toys to retailers and customers globally. They also outsource the manufacturing of their toys. The toy category is divided into age range and the type to generate unique, innovative and fun to play products using the cutting-edge new technology. The web store provides services to the customers that include functionality to manage user accounts, display product details, search the database, manage the shopping cart, and transact purchases. a) Identify the most appropriate software design model that can be used in the above case and justify your answer. b) Construct a Data Flow Diagram to represent the customer portal.