Thomas Edison's Dominance in the Electric Power Industry Was Struck

Thomas Edison's dominance in the electric power industry was struck a serious blow when his competitors, Nikola Tesla and George Westinghouse, began to use transformers with their alternating current (AC) electric power systems. Edison was unable to use transformers in his direct current (DC) electric power systems because

A) Tesla and Westinghouse held the U.S. patent rights to transformers and prevented Edison from using them.
B) direct current electric power must flow directly from the generator to a home, without passing through any intermediate devices.
C) a transformer requires changing currents in its coils in order to transfer power between those currents.
D) DC electric power must flow through thicker wires than can be used efficiently in transformers.