Which of the following are true in the context of Activation theory of emotions?

A. Level of physiological arousal is a secondary determinant of the intensity and type of emotion experienced

B. High arousal states associated with emotions like excitement or anxiety, and low arousal states associated with emotions like calmness or sadness

C. Brain's reticular activating system (RAS) plays a crucial role in regulating the level of arousal

D. Optimal arousal levels are necessary for effective functioning and emotional regulation