Command to restart workflow from a given task in middle of workflow to last task of workflow

Hi
I am using following procedure to restart a given task somewhere in work flow

  cylc vr gmcylc_u3    ....validate and reload workflow
 cylc play gmcylc_u3  ... needed only, if workflow already stopped
 cylc trigger gmcylc_u3//^/Prep  ; trigger aka rerun Prep task; ^ ==> from first cycle

What will be the command to say, a) run all tasks starting from Prep to last task of workflow b) start from Prep to finish following 5 tasks c) start from Prep task, and finish upto say Runmodel