In Terms of the Genetics of Bipolar Disorder, If One

In terms of the genetics of bipolar disorder, if one identical twin develops bipolar disorder, then ________.

A) the other twin always develops bipolar disorder
B) there is a 40 to 70 percent chance that the other twin will also develop the disorder
C) there is a 5 to 10 percent chance that the other twin will not develop the disorder
D) the other twin will show resistance toward the disorder