Increased activity in the during rem sleep may best explain why dream images are often accompanied by a strong emotional tone. pineal gland suprachiasmatic nucleus frontal lobes amygdala

Amygdala is the correct answer.

The amygdala is a portion of our brain responsible for detecting emotions, emotional behavior and the motivation that leads us to act a certain way in specific situations. During our REM sleep, the amygdala (along with the hippocampus) is the part of the limbic system that gets very active which explains why dream images are often followed by a strong emotional tone.