Look at the Following Code

Look at the following code. Which line will cause a compiler error?
Line 1 public class ClassA
Line 2 {
Line 3 public ClassA() {}
Line 4 public final int method1(int a) {}
Line 5 public double method2(int b) {}
Line 6 }
Line 7 public ClassB extends ClassA
Line 8 {
Line 9 public ClassB() {}
Line 10 public int method1(int b) {}
Line 11 public double method2(double c) {}
Line 12 }

A) 4
B) 5
C) 10
D) 11