If a hot air balloon is seen rising above the top of a hill, what is the top of the hill called?

If you see that a hot-air balloon is rising above the top of a hill, what is the top of the hill called?

A. delta point

B. distance system

C. coordinate system

D. reference point

hope it helps :)

electrical potential energy =0.072 j

explanation:

electrical potential energy is given by

u= q δv

q= charge=6 c

δv= potential difference and is given by

δv= e d

e= electric field

d= distance=5 mm=0.005 m

δv=2.4 (0.005)=0.012 v

now electric potential energy= u= q δv

u=6 (0.012)

u=0.072 j