Which Statement Is TRUE Concerning the Development of Bipolar Disorder

Which statement is TRUE concerning the development of bipolar disorder among older adults?

A) The late-life development of bipolar disorder is relatively common.
B) When bipolar disorder develops late in life, there is usually no history of major depression or mania earlier in life.
C) Medical rather than genetic factors are usually associated with the late-life onset of bipolar disorder.
D) When bipolar disorder develops late in life, the intervals between the manic and depressive episodes tend to be fairly long.