Answer:
(D)Multiply the previous value by 2
Step-by-step explanation:

From the given table, we observe that the negative power of 2 reduces by 1 at each step.

Therefore, as the exponents increase, we multiply the previous value by 2 to obtain the next value.
The correct option is D.
-9-(-12)=-9+12=3
-9-12=-9+(-12)=-21