What Is the Difference Between Primary Hypertension and Secondary Hypertension

What is the difference between primary hypertension and secondary hypertension?

A) Secondary hypertension is not as severe as primary hypertension.
B) Primary hypertension usually occurs at an earlier age than secondary hypertension.
C) Secondary hypertension is caused by another health problem,whereas primary hypertension does not have a known cause.
D) Primary hypertension can be treated with antihypertensive drugs,whereas secondary hypertension does not respond to drug therapy.