The determinant of the matrix $$\begin{bmatrix}7 &0 & 0 & 0 \\9 & 3 & 0 & 0 \\4 & -6 & -2 & 0 \\0 & 0 & 0 & 1 \end{bmatrix}$$ is

A

0

B

1

C

-42

D

-68