At the Top of a Cliff 80 M High,Raoul Throws

Multiple Choice

At the top of a cliff 80 m high,Raoul throws a rock upward with velocity 11.0 m/s.How much later should he drop a second rock from rest so both rocks arrive simultaneously at the bottom of the cliff?
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A) 6.58 s
B) 2.39 s
C) 4.34 s
D) 1.27 s
E) ​0.64 s