Which of the following are the correct ways to define an array of 2 rows and 3 columns?

1. int[ , ] a;
   a = new int[2, 3]{{7, 1, 3},{2, 9, 6}};

2. int[ , ] a;
   a = new int[2, 3]{};

3. int[ , ] a = {{7, 1, 3}, {2, 9,6 }};

4. int[ , ] a;
   a = new int[1, 2];

5. int[ , ] a;
   a = new int[1, 2]{{7, 1, 3}, {2, 9, 6}};

1. A class can implement multiple interfaces.
2. Structures cannot inherit a class but can implement an interface.
3. In C#.NET, : is used to signify that a class member implements a specific interface.
4. An interface can implement multiple classes.
5. The static attribute can be used with a method that implements an interface declaration.

1. Data
2. Class
3. Enum
4. Structure
5. Namespace

namespace CuriousTabConsoleApplication
{ 
    class SampleProgram
    { 
        static void Main(string[] args)
        { 
            int[]arr = newint[]{ 1, 2, 3, 4, 5 }; 
            fun(ref arr);
        }
        static void fun(ref int[] a)
        { 
            for (int i = 0; i < a.Length; i++)
            { 
                a[i] = a[i] * 5; 
                Console.Write(a[ i ] + " "); 
            } 
        } 
    } 
}