$1.$ Agile software development refers to software development methodologies centred around the idea of iterative development, where requirements and solutions evolve through collaboration between self$-$organising cross$-$functional teams. a$)$ Describe the SCRUM model of agile development with reference to the key characteristics and different roles involved. $(25$ percent$)$ b$)$ Critically discuss, usmg case studies explored in class, the opportunities and challenges associated with distributed agile development projects. Students should ensure that their answer does not overlap with part $($a$).(25$ percent$)$