Low levels of which neurotransmitters are related to depression?

Low levels of norepinephrine and serotonin are both associated with depression, making the choice encompassing both these neurotransmitters the correct one.

Norepinephrine plays a crucial role in mood regulation and arousal. When its levels are low, individuals may experience symptoms of depression such as lack of energy, motivation, and an overall low mood. Similarly, serotonin is often referred to as the "feel-good" neurotransmitter, and it contributes significantly to feelings of well-being and happiness. Reduced serotonin levels can lead to emotional instability and depressive symptoms.

While acetylcholine is involved in various neurological functions, including memory and learning, its direct relationship to depression is less well-established than that of norepinephrine and serotonin. Thus, the focus on the two neurotransmitters, norepinephrine and serotonin, highlights their proven roles in influencing mood and emotional health, reinforcing the rationale for the correct answer.