trigger ClosedOpportunityTrigger on Opportunity (after insert,after update) {
List<task> carry=New List<task>();

  for(opportunity opp:trigger.new){
   if(opp.stagename=='closed own'){
    task t=new task(whatid=opp.id);
    carry.add(t); 
    }
   }
     insert carry;

 }

 The trigger will add a task to any opportunity inserted or updated with the stage of 'Closed Won'. The task's subject must be 'Follow Up Test Task'.The Apex trigger must be called 'ClosedOpportunityTrigger'
With 'ClosedOpportunityTrigger' active, if an opportunity is inserted or updated with a stage of 'Closed Won', it will have a task created with the subject 'Follow Up Test Task'.
To associate the task with the opportunity, fill the 'WhatId' field with the opportunity ID.
This challenge specifically tests 200 records in one operation.

I tried with the above code, task is not created.