有如下类说明: class TestClass{ int x; public: TestClass(int n){x=n;} }; class TestClass1:public TestClass{ int y; public: TestClass1(int a,int b); }; 在构造函数TestClass1的下列定义中,正确的是( )。
A.TestClass1::TestClass1 (int a,int b):x(a),y(b){}
B.TestClass1::TestClass1 (int a,int b):TestClass(a),y(b){}
C.TestClass1::TestClass1 (int a,int b):x(a),TestClass1(b){}
D.TestClass1::TestClass1 (int a,int b):TestClass(a),TestClass1(b){}