Answer: Hipparchus & Ptolemy believed sun and moon travel around circles with Earth in the middle (geocentric) while Plato and Aristotle believed Perfect unchanging heavens
Explanation: thus hipparchus and ptolemy violate early greek philosophy
The answer is to remove 4 electrons.
I think one hour, sorry if i'm wrong
When a pendulum is at the midpoint of its oscillation, hanging straight down ...
-- that's the fastest it's going to swing, so its kinetic energy is maximum;
and
-- that's the lowest it's going to get, so its potential energy is minimum.
'c' is your choice.