Answer:
The second line from the top
Explanation:
To solve -4 - (-8), start at the origin (0) and go left 4 units. That's the small arrow underneath the longer one. Be careful with the scale on the number line: each space is worth 2 units.
So from -4 subtract -8 by going to the RIGHT 8 units (4 spaces). You go to the right because you are SUBTRACTING -8. (If you were adding -8, you'd go to the left.)
You end up at 4.