Sorry still can't understandcan anyone helpThank you

Problem 5. Two stones are thrown simultaneously from a height of 500 m. The first stone is thrown vertically downward at a speed of 10 m/s, while the second stone is thrown vertically upward at a speed of 10 m/s. Immediately after the two stones are thrown, the difference in their speeds will During the time interval that both stones are in flight the difference in their velocities will (A) increase with time, increase (B) increase with time, stay the same (C) stay the same, stay the same (D) decrease with time, increase (E) decrease with time, decrease