Which sentence best explains the problem of power variability seen in generating electrical energy from wind energy?

A. The power generated by a wind farm is not constant because of irregular wind patterns.

B. Wind energy can only generate alternating voltages and not constant voltages.

C. Transformers used in wind farms only work with alternating voltages.

D. Wind turbines require installation in a zigzag pattern to make efficient use of the force of winds.

E. Variable transformers are required to increase electric voltage generated by wind turbines.