What is the main effect of using the syntax 'del my_list[:]'?

The syntax 'del my_list[:]' is used to delete the contents of the list referred to by the variable my_list. This operation modifies the list in place, effectively clearing all the elements from it, meaning that after executing this statement, my_list will exist as an empty list, although the variable my_list itself still holds a reference to the list object.

Understanding how slice notation works is key here. The expression my_list[:] creates a shallow copy of the entire list, and when using del on that slice, it removes all items from the original list. Therefore, while the variable my_list remains in scope, its contents have been emptied.

In contrast, the other choices imply operations that do not accurately describe the behavior of this command. For example, deleting the list itself or clearing the variable reference would involve different syntax, and deleting the list object from memory entirely is not what occurs here since the variable still retains its reference to the list object; it simply points to an empty list.