lf Tr $\left(A\right)=6$ then Tr $\left(4A\right)=$

The correct option is D. $24$
$Tr\left(A\right)$ is the sum of the diagonal elements of $A$.

Now, $4A$ gives each element of $A$ multiplied by $4$, then

$Tr\left(4A\right)=4\times$ the sum of diagonal elements of $A$

$Tr\left(4A\right)=4\times Tr\left(A\right)$

$Tr\left(4A\right)=4\times 6$
$Tr\left(4A\right)=24$