Answer:
D, or the fourth option.
Explanation:
It would be the fourth option, or D.
If you fold them back up it would look like the picture shown.
We can eliminate options b and c because it's a rectangular prism and their nets show squares NOT rectangles.
Now, try to think and fold up the top most and bottom most fold, then keep the middle rectangle as the base.
Finally, fold up the sides to get the solid figure above (rectangular prism).