Can you please explain the points
3. anonymous_class is-NOT-a C.
4. C is-NOT-a(n) anonymous_class.
We have
interface Cat{}
class A{}
class C extends A implements Cat{}This gives a class structure that looks like this:

This is the statement in the question :
c=(C)new Cat(){};In this line, we are trying to create an anonymous inner class by implementing Cat. Adding that to our diagram, it would look like this:

As you can see in the above diagram, our anonymous inner class is NOT a sub-type of C, which means it does NOT share an is-a relationship C. On the other hand, C is NOT a sub-type of our anonymous inner class anyway, so there is no is-a relationship in that direction either.
Does that make it a clear?