I believe the answer is potential difference
no because nuclear energy come from kinetic not potential energy. burning a wax candle is an example of heat/thermal energy .
Answer:
1000 kgm²/s, 400 J
1000 kgm²/s, 1000 J
600 J
Explanation:
m = Mass of astronauts = 100 kg
d = Diameter
r = Radius = 
v = Velocity of astronauts = 2 m/s
Angular momentum of the system is given by

The angular momentum of the system is 1000 kgm²/s
Rotational energy is given by

The rotational energy of the system is 400 J
There no external toque present so the initial and final angular momentum will be equal to the initial angular momentum 1000 kgm²/s

Energy

The new energy will be 1000 J
Work done will be the change in the kinetic energy

The work done is 600 J
I think it is A) but someone might need to double check that.
This applies to nuclear reactions, specifically nuclear fission.
This huge release of energy has been used in atomic bombs and in the nuclear reactors that generate electricity.