2D Motion

My daughter throws a 50 gram stone at 1 m/s horizontally from a bridge above a river at the same time my son drops a 100 g stone off the bridge. Which one hits the water first?
A. 50g    B. 100g    C. Same time    D. Depends on the mass of each?

Then draw a diagram of the experiment, showing the acceleration vectors and velocity vectors at several key points in your experiment.