The correct option is
a fire
In fact, a fire is a conversion of chemical energy (contained in the molecules of the initial substances) into thermal energy (the heat released by the fire itself), therefore this is an example of energy changing from one form to another. All the other objects, instead, do not represent any form of energy conversion.
The electrostatic force between two charges Q1 and q is given by

where
ke is the Coulomb's constant
Q1 is the first charge
q is the second charge
r is the distance between the two charges
Re-arranging the formula, we have

and since we know the value of the force F, of the charge Q1 and the distance r between the two charges, we can calculate the value of q:

And since the force is attractive, the two charges must have opposite sign, so the charge q must have negative sign.
tectonic plates rubbing against each other.
Answer:
D. the ability to exercise for longer periods of time
Explanation:
For example, when someone does endurance training, they are stretching their body's ability to do a certain exercise for longer times as opposed to increasing strength.
When rain falls on the land, it either seeps into the ground or becomes runoff, which flows downhill into rivers and lakes.