Which character from the short story “rules of the game” by amy tan is motivated by a desire to master “invisible strength” in life and in chess?

The character of the story "Rules of the Game" written by Amy Tan who is described to be invincible in chess is Waverly Place Jong also known as Meimei. Although she cannot find any opponent who can eventually beat hear in chess, she finds a bigger opponent at home- her mom. 

Iwould think that the correct answer is 8.1