阅读和理解下面程序段: class Manager extends Employee{ public Manager(String n,double s,int year,int month,int day){super(n,s,year,month,day);bonus=0; } public double getSalary(){double baseSalary-super.gerSalary();return baseSalary+bonus; } public void setBonus(double b){bonus=b; ) private double bonus; } Manager是Employee的子类,其理由是( )。
A.Manager的适用范围较宽
B.extends关键字声明
C.Manager的域减小了
D.雇员是一个经理