Wind energy spins the blades on this wind turbine. the mechanical energy of the moving blades is used to generate electricity. but wind turbines are not suited to all areas of the country, because in some places there is not enough wind.

why is an external energy source, in this case wind, needed to keep the blades spinning?
a) wind energy is required for energy transformations.
b) without an external energy source, friction stops the blades.
c) wind energy is required to convert potential energy to kinetic energy.
eliminate
d) the internal energy will overcome the external energy and the blades will stop spinning.