I believe it's Mercury, because the only other option would be Pluto and it's not even considered a planet anymore
Hope this helps
Now let’s say you’re on the Moon. If you were to drop a hammer and a feather from the same height, which would hit the ground first?
Trick Question! On the moon both objects would hit the ground at the same time. On Earth, the hammer lands first.
So yeah, the student is right. Galileo gave us this theory long ago.
To solve the problem we will simply perform equivalence between both expressions. We will proceed to place your units and develop your internal operations in case there is any. From there we will compare and look at its consistency


At the same time we have that



Therefore there is not have same units and both are not consistent and the correct answer is B.
A sound wave is a longitudinal wave caused by vibrations and carried through a substance. The particles of the substance, such as air particles, vibrate back and forth along the path that the sound waves travel. Sound is transmitted through the vibrations and collisions of the particles.
This could maybe help you with your answer.