A boy throws a small stone into a pond. Waves spread out from where the stone hit the water and travel to the side of the pond. 10 waves reach the side of the pond in four seconds. What is the frequency of the waves?

A 0.4Hz
B 1.6Hz
C 2.5Hz
D 40 Hz

it is very well related to a lot of things but with my limited knowledge i can confidently say that the answer is space.

a electromagnetic waves

answer;

d. are made mostly of liquid

explanation;

-the general   composition and structure planets includes; they have a thick gas and liquid layer covering a small,solid core. mostly the gases are hydrogen and helium atmosphere and layers of liquid hydrogen. for instance neptune and uranus are examples of the outer planets, they have a core covered by ice and ammonia.

-neptune's atmosphere is hydrogen and helium with a bit of methane so there is no oxygen to breath and the interior is made up of frozen water and ammonia with a rock and iron core. thus, there is no liquid water or solid surface to survive.

conduction, convection, radiation