Consider the following statements in respect of a skew-symmetric matrix A of order 3 :
1. All diagonal elements are zero.
2. The sum of all the diagonal elements of the matrix is zero.
3. A is orthogonal matrix.
Which of the statements given above are correct?
1
1 and 2 only
2
2 and 3 only
3
1 and 3 only
4
1, 2 and 3