Final answer:
Clinical depression is a serious condition caused by a chemical imbalance in the brain, resulting in various symptoms that interfere with daily life and often requires treatment. The correct answer is option A) caused by a chemical imbalance in the brain that interferes with daily functioning.
Step-by-step explanation:
Clinical depression is caused by a chemical imbalance in the brain that interferes with daily functioning. It is characterized by a severely depressed mood that lasts for more than two weeks, along with other symptoms such as changes in appetite and sleep schedules, difficulty concentrating, feelings of worthlessness, and possibly sui-cidal thoughts. The exact causes of major depression are complex, involving both genetic and environmental factors, and can include a decrease in neurotransmitters like norepinephrine and serotonin. It is a serious condition that often requires treatment, which can consist of psychotherapy, medication, or other therapies such as electroconvulsive therapy and deep-brain stimulation.