50. According to the passage, why does psychologist Paul Ekman conclude that “emotion is the least plastic part of the brain”?
(A) Once an emotional association is made, it is difficult to unmake it.
(B) The refractory period is aware of what triggers our various emotions.
(C) Idyllic childhood summers spent in the country arouse strong emotions.
(D) Emotional triggers are more easily forgotten than remembered in old people