Read the passage carefully and select the correct answer for the given blanks out of the four alternatives.
The causes of bipolar disorder aren't completely understood, but it often (1) ________ to be hereditary. The first manic or depressive episode of bipolar disorder usually (2) ________ in the teenage years or early adulthood. The symptoms can be subtle and confusing; many people with bipolar disorder are overlooked or misdiagnosed-resulting in unnecessary (3) ________. Since bipolar disorder tends to worsen without treatment, it's important to learn (4) ________ the symptoms look like. Recognizing the problem is the first step to feeling better and getting your life back on (5) ________.