45. Consider: radio waves (r), visible light (v), infra-red (i), x-rays (x), ultraviolet (u). In order of increasing frequency, they are:
(A) r, v, i, x, u
(B) r, i, v, u, x
(C) i, r, v, u, x
(D) i, v, t, u, x
(E)r, i, v, x, u
答案：B
統計：A:0,B:1,C:0,D:0,E:0
難度：計算中