(51) Which of the followings is wrong about this representation of N? (A) There can be more than one digit for a. (B) The representation can be found by a greedy algorithm. (C) We can use it as a number system to represent positive integers. (D) This representation can be generalized as N= Bino(a, 4) + Bino(b, 3) + Bino(c, 2)+ Bino(d, 1), where a ＞ b＞ c＞ d ＞=0. (E) The representation may not be unique for some positive N.