A 20-Kg Child Sits on a See Saw on the Playground,3.0

A 20-kg child sits on a see saw on the playground,3.0 m from the pivot.A 2^nd child is seated on the other side of the pivot and 2.00 m from the pivot.The mass of the second child needed to lift the first child off the ground is

A) 20 kg.
B) 30 kg.
C) 40 kg.
D) 50 kg.