A stone thrown down with a speed u takes a time t₁ to reach the ground, while another stone, thrown upwards from the same point with the same speed, takes time t₂. The maximum height of the second stone reaches from the ground is :
A. 1/2 160;gt₁t₂
B. g 8 (t₁+t₂)²
C. g 8 (t₁−t₂)²
D. 1/2 gt₂²