One of the central ideas behind the practice of Schedule Risk Analysis $($SRA$)$ is that

Multiple Choice

Activities should not be classified in a binary way: critical activities versus non$-$critical activities.

Adding alternative subgraphs will decrease the variation of estimated activity durations.

It is crucial to determine the most critical activity in a project and remove it from the schedule.

The project becomes a lot more manageable after removing the critical path from the schedule.