The diagonal elements of a skew symmetric matrix are all

The correct answer is Option (1) → 0

A matrix A is called skew-symmetric if A^T = -A.

This implies that for any entry a_ij}, it must hold that:

$a_{ij} = -a_{ji}$

In particular, for diagonal elements, where i = j:

$a_{ii} = -a_{ii}$

This implies:

$2a_{ii} = 0 \Rightarrow a_{ii} = 0$

Hence, all diagonal elements of a skew-symmetric matrix are zero.