Answer:
B) Force of gravity
Explanation:
As it is the force which acts downward on the body towards the ground, it is clearly the force gravity represented by the arrow at A.
The wavelength of a wave (λ) is given by λ

where c is the wave speed and f is the frequency
I believe Corn is a natural resource. It is a type of cereal plant grains, grown on Farms.
D is the answer
I hope it helps!
True because they will work good with eachother