Answer:
The piece of evidence that best reveals the lose-lose reality of the king's arena is:
B "It mattered not that he might already possess a wife and family, or that his affections might be engaged upon an object of his own selection" (Paragraph 6).
Explanation:
"The Lady, or the Tiger?" is a short story by American author and humorist Frank Richard Stockton. A semi-barbaric king came up with what he considered to be the fairest of trials. The criminal had to choose one of two doors to open. If he opened the door behind which a tiger was hiding, he would immediately be judged guilty, and he'd be punished by the tiger. If he opened the door behind which a damsel was waiting, he would have to marry her on the spot.
Notice that this is a lose-lose situation. The reward is not really a reward. That man does not wish to be married to that woman - and she doesn't wish that either. They do not know nor love each other. He gets to live instead of being killed by the tiger, but he is bound to have a miserable life with someone he never wanted. The piece of evidence that best reveals precisely that is:
B "It mattered not that he might already possess a wife and family, or that his affections might be engaged upon an object of his own selection" (Paragraph 6).
So, even if the man is in love with someone else - even if he is already married -, he still has to marry the damsel.
