Question

in the fire starting video, which forms of energy are being transferred?
nuclear energy to thermal energy.
mechanical energy to heat energy
heat energy to chemical energy
thermal energy to potential energy.

Explanation:

When starting a fire (e.g., using a bow - drill), mechanical energy (from the motion of hands or tools) is used. Friction due to this mechanical motion generates heat. So, mechanical energy is converted to heat (thermal) energy. Nuclear energy involves processes like fission/fusion (not in fire - starting). Heat to chemical would be like in some endothermic reactions (not fire - starting). Thermal to potential is not relevant here as potential energy is stored energy based on position.

Answer:

mechanical energy to heat energy