给定如下C++代码：

#include <iostream>
using namespace std;

class Base {
private:
    int a;
protected:
    int b;
public:
    int c;
    Base() : a(1), b(2), c(3) {}
};

class Derived : public Base {
public:
    void show() {
        cout << a << endl;   // Line 1
        cout << b << endl;   // Line 2
        cout << c << endl;   // Line 3
    }
};

（ ）行代码会引起编译错误。