Es cuando una onda sonora topa en una superficie?

i think it was A

Explanation:

im not sure

there are the initial camera costs, with each camera running about $1,000, but the storage costs are where the real expense comes in. according to a recent time article online, nearly a third of the 18,000 state and local police departments in the u.s. are purchasing body-cameras for their officers.

it would usually depend on the genre that they would provide