狒狒数学一题看不懂。。。

看不懂这道题什么意思。。。高手帮忙解释一下吧！

For all x, x is positive integer. "2-height" is defined to be the greatest nonnagative n of x, what is the greatest number of the 2-height when 2" is the factor of x?

A. 2

B.12

C.40

D.76

E.90

For all x, x is positive integer. "2-height" is defined to be the greatest nonnagative n of x, what is the greatest number of the 2-height when 2^n is the factor of x