[单选题]Directions: In this part there is a sentence with four choices marked A, B, C and D. Choose the one that best completes the sentence.（ ） truly changes the world is the way you look at yourself.
A
When
B
What
C
Who
D
How
正确答案：B
题目解析
分析句子可知（ ） truly changes the world作is的主语，为主语从句。在主语从句中，changes缺少主语，结合句意可以确定需要可以指代事物并能在从句中作主语的what来引导，故选B。when和how均不能在从句中做主语，who指代人，不符合句意，均排除。
