单选题 To understand what true happiness is one must ______.

A、 have as much fun as possible during one's lifetime
B、 make every effort to liberate oneself from pain
C、 put up with pain under all circumstances
D、 be able to distinguish happiness from fun

【正确答案】 D

【答案解析】关键在于区分内心的幸福感悟和外在的欢腾表象。