What is the defining characteristic of a manic episode? a. Elevated or irritable mood lasting at least one week b. Depressive mood for at least two weeks c. Reduced energy levels d. Social withdrawal

The correct answer is a. Elevated or irritable mood lasting at least one week.<br /><br />A manic episode is a elevated, expansive, or irritable mood and persistently increased activity or energy, lasting at least one week. This is a key characteristic of bipolar disorder and other mood disorders. The other options, such as depressive mood, reduced energy levels, and social withdrawal, are more characteristic of depressive episodes, not manic episodes.