57.14 A sound wave traveling downward with a speed of about 4,000 m/s suddenly slows to 1,500 m/s not far below the
Earth's surface.
What has the sound wave most likely encountered?
a different kind of rock
O an underground lake
an open cavity
O a pile of dinosaur bones

an underground lake

Explanation:

I took the test

wavelegth as in spectrum red oygbiv

as we probably am aware that our atmosphere or air have various levels, each level has different gasses, and each gas has another porousness. at the point when the light originates from lower porousness to higher penetrability, it alters its course. with the goal that implies that when the light originates from the moon to the earth, it alters it's course a lot more occasions. it essentially implies that the state of the light piece of the moon is changed on the earth.

not copied too! hope this !

joke:

h o h o hope you have a merry christmas!