A context switch occurs when the scheduler changes the running process. Select all of the following statements that are true (incorrect selections gain negative marks). Select one or more: 1. A context switch can only occur at points in a program determined by the programmer. 2. A context switch causes all the process's memory pages to be de-allocated. 3. A context switch can be caused by the completion of an 1/0 event requested by another process. 4. A mode switch always leads to a context switch (i.e. the process that was in the running state before the mode switch is guaranteed to not be in the running state straight after the mode switch). 5. A context switch is not the same as a mode switch. 6. The state of all the user visible processor registers need to be saved--including the program counter and stack register