Answer:
b. they get blown in from colder or warmer areas.
Answer: The average velocity is 150 km/h
Explanation: 70+80=150
No, not exactly. They jiggle and tremble and vibrate a lot, but
they always basically stay in very nearly the same place.
It's like if you're allowed to go anywhere you want in your jail cell,
you wouldn't exactly call that "moving about freely".
Answer: An 8 kg book at a height of 3 m has the most gravitational potential energy.
Explanation:
Gravitational potential energy is the product of mass of object, height of object and gravitational field.
So, formula to calculate gravitational potential energy is as follows.
U = mgh
where,
m = mass of object
g = gravitational field = 
h = height of object
(A) m = 5 kg and h = 2m
Therefore, its gravitational potential energy is calculated as follows.

(B) m = 8 kg and h = 2 m
Therefore, its gravitational potential energy is calculated as follows.

(C) m = 8 kg and h = 3 m
Therefore, its gravitational potential energy is calculated as follows.

(D) m = 5 kg and h = 3 m
Therefore, its gravitational potential energy is calculated as follows.

Thus, we can conclude that an 8 kg book at a height of 3 m has the most gravitational potential energy.