Let $y = - 5$ And $z = - 4$ Find $$D = y - z$$

Multiple Choice

Let $y = - 5$ and $z = - 4$ . Find $$D = y - z$$

A) $D = 9$
B) $D = - 1$
C) $D = - 9$
D) $D = 1$
E) none of these