Which type of wave does not require a medium to travel through?

A.
wave created by x-rays as they create an image of a bone

B.
wave created by plucking the strings of a guitar

C.
wave created by dropping a pebble in water

D.
wave created by squeezing and releasing a spring

Question

Which type of wave does not require a medium to travel through?	
 
 A.
wave created by x-rays as they create an image of a bone
 
 B.
wave created by plucking the strings of a guitar
 
 C.
wave created by dropping a pebble in water
 
 D.
wave created by squeezing and releasing a spring

anonymous · Answer

hmm mechanical waves need medium to trave
while elecromagnetic dont need any medium
sound and water waves need medium they are mechanical waves 
while x-rays dont as they are electromagnetic 
so A as its pointing toward x-rays 
but B D towards sound waves and c towards water waves