Which of these is not a possible type of energy transformation?
a. light energy into nuclear energy
b. electrical energy into light energy
c. kinetic energy into potential energy
d. geothermal energy into electrical energy

It would be A because Light energy can't be used to make a Nuclear Weapon.
Electricity turns on a light bulb so B is scientifically correct.
If potential energy can be turned to Kinetic, it can also be switched. so C is scientifically correct
Ever heard of Geothermal power plants? So D is scientifically correct.
Meanwhile, A is impossible. so it is the answer you want to choose. Because the question asked for the one which is impossible.