Prevent other classes from altering a list in a class

Question

If I have a class that contains, for example, a List and I want other classes to be able to see the list but not set it, I can declare

Answer 1

Return IEnumerable, which is immutable. The getter should look like this:

public IEnumerable SomeList
{
   get
   {
      foreach(string s in someList) yield return s; // excuse my inline style here, zealots
      yield break;
   }
}