What Impact Does the Use of Lithium Have on Depressive

What impact does the use of lithium have on depressive episodes?

A) Lithium has no effect on depressive episodes.
B) Because lithium completely stops manic episodes, it also stops all depressive episodes.
C) Lithium is an effective treatment for unipolar depression.
D) Lithium helps people with bipolar depression overcome their depressive episodes, though to a lesser degree than it helps with their manic episodes.