Which of the followings about swimlanes in activity diagrams are correct $($choose all that apply$)?$

Swim lanes can only be arranged vertically.

All the processes in different swimlanes can be executed paralelly.

Fork node is used to bring back together a set of parallel or concurrent flows of activities

Swimlanes show who is responsible for each activity; but they are also helpful in identifying the activities that can cause delays

Each swimlane represent a set of operations that is performed by one user$/$group$/$system