I would like to automatically add a topic to Question asked in the Community.
I have the following apex trigger that works for all posts. But I would like to add in a statement that ONLY makes it works on Question type posts on a community and not internal org.

Thanks in advance.

trigger AddingQtopic on FeedItem (after insert) {
      List<TopicAssignment> taList = new List<TopicAssignment>();
    for(FeedItem c : trigger.new){
  TopicAssignment ta = new TopicAssignment();
  ta.TopicId = '0TO400000000NCE';
  ta.EntityId = c.Id;  
        taList.add(ta);
    
    insert taList;    
        }
    }