At the Top of a Cliff 100 M High,Raoul Throws

Multiple Choice

At the top of a cliff 100 m high,Raoul throws a rock upward with velocity 20.0 m/s.How much later should he drop a second rock from rest so both rocks arrive simultaneously at the bottom of the cliff?

A) 5.05 s
B) 3.76 s
C) 2.48 s
D) 1.78 s