Consider the following code snippet: #ifndef cashregister_h#define cashregister_hconst double max_balance = 6000000.0; class cashregister{public: cashregister(); cashregister(double new_balance); void set_balance(double new_balance); double get_balance() const; private: double balance[12]; }; double get_monthly_balance(cashregister bk, int month); #endifwhich of the following is correct? a)the header file is correct as given. b)the definition of max_balance should be removed since header files should not contain constants. c)the definition of cashregister should be removed since header files should not contain class definitions. d)the body of the get_monthly_balance function should be added to the header file.