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(A)misunderstanding 
(B)discussion 
(C)  conversations  
(D)understanding 

Research into behavioral economics has shown that our assessment評估；估價；評估結果 of what something is worth值得 to us can be directly, and predictably預料中地, influenced影響，作用；有影響的人（或物）.

This is the illusion幻覺，幻想 of the free lunch, something humans are known 46 even when economic theory would clearly suggest we select a more valuable option at a small cost.

Researchers also found how we sometimes operate on social norms社会规范, while other times we fall into market norms规范.

The difference is in whether there is a price attached to something.

If a friend invites you over for dinner, she will probably appreciate it if you bring a nice bottle of wine along (social norms社会规范).

However, if instead作為替代 you throw $20 (the price of a nice bottle of wine) in cash on the table and say “thanks for a lovely dinner,” she would most likely 47 (market norms规范).

Mixing social norms社会规范 and market norms社会规范 inappropriately不適合的；不恰當的 often leads to導致 irrational不理智的，沒有理性的 behavior and, possibly, even to conflict or 48 .

conversation翻譯：交談，談話，對話。