A square matrix $B=[bij]_{n×n}$ where
$bij =0 $ when i≠j
$bij= k$ when $i=j$ for some constant k is called :
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → Scalar matrix
$B_{n×n}=\begin{bmatrix}k&0&0...&0\\0&k&0...&0\\....\\0&0&0...&k\end{bmatrix}$
so $B=KI_n$
so B is a Scalar matrix