The correct answer is 3. Bipolar depression, also known as bipolar disorder depression or depressive phase of bipolar disorder, is a significant aspect of bipolar disorder, a mental health condition characterized by mood swings that range from episodes of elevated or "manic" states to episodes of depression. Bipolar disorder is marked by its cyclic nature, with periods of mood elevation and increased energy (manic or hypomanic episodes) alternating with periods of low mood and energy (depressive episodes).