If $\mathrm{A}=\left[{\mathrm{a}}_{\mathrm{ij}}\right]$ is a scalar matrix of order n x n such that ${\mathrm{a}}_{\mathrm{ij}}=\mathrm{k}$ for all i=j, then trace of A is 

• A

  k

• B

  nk

• C

  n

• D

  none of these