有答案有思路还是看不明白的数学题(请nn帮忙)

eachjun

10、For all x, x is positive integer,  "2-height" is defined

    to be the greatest nonnegative n of x, what is the

    greatest number of 2-height when 2" is the factor of x?

A. 2

B. 12

C. 40

D. 76

E. 90

 

【答案】C

【思路】：40=2^3 *5,  2的幂最多