Requirement engineering help us to understand the user requirements in a systematic way. We model requirements in the requirement analysis phase and do the design of the system in the design phase. a. Explain the main difference between Analysis classes and design classes. b. When do you use a design pattern? Explain the advantage of using a design pattern. Identify the design classes for the following scenario. You need to specify the relationship among the design classes. Include appropriate methods in each design class. There is a medical facility, and they wish to have a system developed to help their daily activities. The followings are the listed requirements. The medical facility has several doctors visiting them to check patients. Any doctor is descried by SSN, FirstName, LastName, Speciality, YearsOfExperience, and PhoneNumber The facility also records patient information which include SSN, FirstName LastName, Address, DOB. Each Patient has a Primary Doctor. Patient must have the primary doctor assigned at the time of registration. A patient can be seen by the primary doctor or any other doctor and prescribe medications. Any prescription needs to have a date of prescription. Prescription is described by the TradeName, and Units. Medicine is recorded in a separate entity called Medicine which is described by TradeName, UnitPrice, and GenericFlag.