In your own words, explain why longitudinal waves cannot travel in space.

Longitudinal waves are compressional waves which means they travel in one direction and do not radiate out.

They are created by continuous intermittent compression and thus will have sparse spacing and then compressed and then sparse, compressed and so on.

Such wave requires a medium such as solid liquid or air to travel thru.

I hope this helps ^-^

A) early horses is your answer