Answer: Bipolar Disorder
Explanation: Bipolar disorder (formerly called manic-depressive illness or manic depression) is a mental illness that causes unusual shifts in a person's mood, energy, activity levels, and concentration. These shifts can make it difficult to carry out day-to-day tasks. There are three types of bipolar disorder. It has a strong genetic component with high monozygotic twin concordance and estimates of heritability from population-based twin samples reported as high as 93%. This means that if one twin has bipolar disorder, there is a high chance that the other twin will also have the disorder. The concordance rates for schizophrenia and major depressive disorder are also high, but bipolar disorder has the highest rate among the options given.