The correct answer is option 2.

In a vertical motion scenario like this, the time-velocity graph should show a symmetrical curve. When the ball is thrown up, it experiences a decrease in velocity due to the force of gravity, until it reaches its highest point where its velocity is momentarily zero. After reaching the highest point, the ball falls down and the velocity increases.

Option 2 represents this motion accurately. The graph starts at a positive value (indicating the initial upward velocity), then decreases to zero at the highest point (indicating zero velocity), and finally becomes negative as the ball falls back down towards the Earth (indicating downward velocity).

Option 1 does not show the symmetrical curve and Option 3 and 4 have incorrect shapes for a vertical motion.

Therefore, option 2 is the only correct representation of the time-velocity graph for a ball thrown vertically in a vacuum.