Which of the following elements produces no harmful emissions when used as an energy source? a. coal b. oil c. wind d. natural gas

Harnessing of the energy derived from the motion of wind is one of the many eyed cleaner sources of energy. All the rest of the choices would produce a negative impact in the environment because of the emissions. The answer is therefore letter C. 

Ithink the answer to that would be b):

Water flows along the east coast and across the western tropical pacific towards south america, while they both are directed towards that way,  el niño does not directly affect the southern flow of water along the coast.