Which of the following is a diagnostic criterion for Bipolar II disorder?

For a diagnosis of Bipolar II disorder, a person must experience at least one major depressive episode alongside one or more hypomanic episodes. The major depressive episode is characterized by symptoms such as significant sadness, loss of interest, and changes in appetite or sleep patterns, while hypomanic episodes involve a period of elevated mood, increased energy, and activity levels, but not to the full extent of a manic episode seen in Bipolar I disorder.

Thus, the correct answer reflects the requirement that both criteria must be met: the presence of at least one major depressive episode and one or more hypomanic episodes. This combination distinguishes Bipolar II disorder from other mood disorders and different forms of bipolar disorder, where manic episodes may be present. In summary, having both a major depressive episode and hypomanic episodes is essential for the diagnosis of Bipolar II disorder.