[单选题]
All electromagnetic waves traveln*w02 sa r* /.ijknauzc)4eik through a vacuu9o,lkauok-c5veq 7j fxj(l)om u6)/ s z i+m,gm at
A. the same speed.
B. speeds that are proportional to their frequency.
C. speeds that are inversely proportional to their frequency.
D. none of the given answers
