The hypothesis asserts that African-Americans are more prone to diseases such as pyelonephritis and syphilis that may result in secondary hypertension.

Associated disorder

Explanation:

Associated disorder hypothesis proposes that the high-frequency hypertension of African-Americans is caused by other diseases such as pyelonephritis and syphilis. There are other hypotheses that can explain the cause too. The genetic hypothesis said that it because the gene of African-Americans is different. The psychological stress hypothesis thinks that discrimination causes stress which leads to higher blood pressure.  

what statement best describes the difference between the sympathetic and parasympathetic nervous systems?

the sympathetic nervous system prepares the body for intense physical activity and is often referred to as the fight-or-flight response. the parasympathetic nervous system has almost the exact opposite effect and relaxes the body and inhibits or slows many high energy functions.