II. Which of the following requires the operating system to run? For those where the OS is need, identify the type of event that causes the OS to start executing (system call, interrupt, fault, etc...). (4 points) a) A program is traversing a linked list b) A process finishes execution and needs to exit c) The linked-list in (a) has a bug and one of the pointers is null. The process derefrences (accesses) this null pointer. d) A network packet is received