If a^5 ≤ a, which of the following must be true?
I. –1 ≤ a ≤ 0
II. a=0
III. 0 ≤ a ≤ 1  Choose the correct choice from the following answers: A) None of the above B) I only C) II only D) III only E) I and III only
The trick here is more on the answer choices.   Look at I II and III. all are right (pick out some numbers).   Therefore I was totally confused because non of the answers had the right answer (I II and III)   I finally chose D, but hesitate between A and D quite a long time...   This is a tricky tricky question, since it takes into consideration that the answers are correct but they do not cover all the POSSIBLE answers.   Therefore it is None of the above.
<result>A</result>
If a^5 ≤ a, which of the following must be true?
I. –1 ≤ a ≤ 0
II. a=0
III. 0 ≤ a ≤ 1