Spinning blades of a windmill would be what kind of energy?
1.)electrical
2.)mechanical
3.)chemical
4.)thermal

If the blades of a windmill are spinning, then the whole assembly
has mechanical (kinetic) energy.

If they were made to spin by a battery and a motor inside, then
the kinetic energy of the blades came from electrical energy, and
they're passing their kinetic energy to air in order to move it.

If they were made to spin by wind blowing past the blades, then
they robbed some of the kinetic energy from the moving air, and
that can be used to turn a generator inside and convert the kinetic
energy into electrical energy.

Electrical, but it only produces a little bit of electrical.