Explanation:
Option a: a method with the "same signature" is allowed in the subclass. There will not be any confusion because the object which is trying to call the method will decide whether to call the sub class or super class.
Option b: a call to a super class constructor is possible because, when you create an object of sub class automatically the super class constructor will be called. Even the sub class constructor can call the super class constructor explicitly.
Option c: A subclass can create method that's not defined by the super class
Option D: a private method is private inside the class and hence even the object of that class cannot access.