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gordon wrote this passage about mechanical waves for his physics class. but he got most of his facts mixed up. only one sentence is correct. which sentence is it?

a) mechanical waves don’t need a medium to travel. when they travel through a vacuum, mechanical waves are oval-shaped. they’re either transverse or double transverse waves.

b) mechanical waves can apply pressure to and push on objects in their path.

c) but they travel slower in denser mediums.