What does "dirty pool" at the end of the second paragraph mean

A．They sensed that something terrible happened, they didn't dare to ask.
B．They were afraid that the writer might lose face if they asked.
C．They’d like to let it be for it was not their business.
D．They tried to calm the writer in this way.

A．A young person cheated of the best things in life.
B．A genius athlete breaks a world record.
C．A little girl suffers from an incurable disease.
D．When the curtain comes down on a touching play.