Bipolar disorder has a rate of heritability suggesting a biological cause.

The answer is high. It is because bipolar disorder does cause high rate of heritability because of factors that could affect the individual. These factors or biological cause can affect greatly in which is why it has been concluded that it could cause high heritability. The factors have been a great contribution in making an individual to be susceptible or acquire this type of disorder.

the answer is :

answer; motor (efferent)neurons;