Q.1 (a) When modelling the problem domain as part of an analysis and design process, designers will prefer unidirectional associations over bidirectional associations unless there is an evident need for bidirectional navigation between objects. Explain, in terms of the implementation of the model, why designers might have this preference. In your answer, provide an example class diagram and code that illustrates your explanation. [15 Marks] (b) (i) The Law of Demeter is also known as the Principle of Least Knowledge. Give a brief summary of this principle. [3 Marks] (ii) Give a brief description of three of the four guides within the Law of Demeter and provide both a class diagram and a sequence diagram that illustrates the structure and behaviour of each one. [15 Marks]