1. The problem asks us to identify which of the given options is NOT a square matrix. 2. A square matrix is defined as a matrix with the same number of rows and columns. 3. Let's analyze each option: - (a) Matrix has 3 rows and 2 columns (3x2), which is NOT square. - (b) Matrix has 3 rows and 3 columns (3x3), which IS square. - (c) A single value (5) can be considered a 1x1 matrix, which IS square. 4. Therefore, the only matrix that is not square is option (a). **Final answer:** Option (a) is NOT a square matrix.