Successful entrepreneurs tend to have a high need for achievement.

If the demand curve of a perfect competitor is tangent to (just touching) the firm's average total cost curve,

A) the firm is definitely in the short run.
B) the firm is probably in the short run.
C) the firm is definitely in the long run.
D) the firm is probably in the long run.
E) there is no way to determine whether the firm is in the short run or the long run.