Final answer:
Edison was unwilling to listen to Tesla's ideas because he believed direct current (DC) was more efficient.
Step-by-step explanation:
Edison was unwilling to listen to Tesla's ideas primarily because a) Edison believed direct current (D.C.) was more efficient. Although Edison eventually adapted to AC power as its popularity increased, he initially fought against it because he believed DC power was superior. This disagreement led to a public relations battle known as "The War of the Currents" between Edison and Westinghouse, who promoted AC power.