Which property describes an electromagnetic wave and not a mechanical wave?
a.
transfers energy
b.
travels in a vacuum
c.
has frequency
d.
requires a medium

The question is asking to state the property that describes an electromagnetic wave and not a mechanical wave, base on my research, I would say that the correct answer among them is in letter B. travels in vacuum. I hope you are satisfied with my answer and feel free to ask for more 

Hi. where is the graph?

Any photo? or something