I want a solution to these questions

Question No 3: Answer Part A, Part B and Part C. 10.00 / 10 Marks 3.00 +2.50 +4.50 = 10.0 Marks Part A: Briefly describe when operating system will be in kernel mode? Draw figure for transition from user-mode to kernel-mode. [1.0+ 2.0 = 3.00 marks] [2.50 marks] Part B: Explain how the variable timer is implemented. [4.50 marks] Part C: Differentiate between; (i) (ii) (iii) Passive entity and Active entity Distributed operating system and Embedded operating system Preemptive multitasking and Cooperative multitasking