what is the similarities of these energies?

Question

a. photovoltaic energy
b. alternative energy
c. nuclear energy
d. plasma energy

Answer 1

Energy comes in different forms -- heat (thermal), light (radiant), mechanical, electrical, chemical, and nuclear energy. Energy is in everything. All of your choices reflect this fact.

Answer 2

All of them are clean energies and are good alternatives to fossil fuel based energy which is the main stay of the world right now and is leading to global warming, acid rains etc.

By the way, there is nothing like alternative energy (b).