Question 4 a) Refer to Figure Q4a for the partial steps for the use case Order Item. If available_count for selected item > 0 Update selected item available_count Add item to order Figure Q4a Several concurrent processes are running Order Item. Discuss whether the following event can happen. Lost update Deadlock Use an appropriate example/scenario including the interleaving steps if an event can arise or provide a reason if it is not possible for an event to happen. (8 marks) b) The use case Order Item is implemented as a stored procedure. Suggest how you can secure the stored procedure e.g., who can execute it. Explain. (2 marks)