To solve the equation \( \frac{x}{-2} = 8 \), you can start by multiplying both sides of the equation by -2 to isolate \( x \):
\[ x = 8 \times -2 \]
Calculating the right side:
\[ x = -16 \]
Therefore, the solution is \( x = -16 \).
The correct answer is: D. \( x = -16 \)