Please choose the correct ending to complete the given sentence: Ping-pong: A robot plays ping pong against a human. a woman

Ending1: plays an older, harder game. Ending2: youtube videos carrying comp-chromosome robots and the two masters talk to each other, then play ping pong. Ending3: walks behind the game. Ending4: plays a black cat on a table.

Answer format: ending1/ending2/ending3/ending4