Is it necessary to call make_immutable in parent class?

Hi,

I am new to Moose and I love this framework.
I have a question regarding to making class immutable.
Suppose I have a class hierarchy as below:

           A
          /
        B
      /   \
     C     D

B is the parent class of C and D.
A is the parent class of B.

Now I want to make class C immutable.

My question is "when I call C->meta->make_immutable(), does it apply to 
only the meta class of C or apply to all its parent classes (B,A) but 
within class C's namespace? In other words, after making class C 
immutable, will it introspect the structure of Class A and B when I 
create a new object? Do I need to call make_immutable for class B and A 
If I want to make Class C immutable?"

Thanks,
-- 
Justin Yao