Wave A has an amplitude of 3, and wave B has an amplitude of 3. What will happen when the trough of wave A meets the trough of wave B?
They will interfere to create a trough with an amplitude of 6.
They will interfere to create a crest with an amplitude of 3.
They will interfere to create a trough with an amplitude of zero.
They will bounce off from one another.

yup its correct its: c) b b

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.