Which class method definitions contain errors in i

Which class method definitions contain errors in it?

 
public class Foo 
{ 
      public void M1(int[] p1, int[] p2) { } 
      public void M2(int[] p1, params int[] p2) { } 
      public void M3(params int[] p1, int[] p2) { } 
      public void M4(params int[] p1, params int p2) { } 
}

There are no errors, everything is defined correctly
M1
M2
M3
M4

Explanation

Additional parameters are not allowed after the one with params keyword. params keyword cannot be used more than once in a method declaration More on it can be found here: https://msdn.microsoft.com/en-us/us-eng/library/w5zay9db(VS.90).aspx