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 15.0 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) 8.08 s
B) 3.31 s
C) 5.02 s
D) 1.78 s
E) ​0.89 s