What Is the Current State of Knowledge on Progression or Regression

What is the current state of knowledge on progression or regression of atherosclerosis in human coronary arteries?

A) Regression of atherosclerosis has been observed in clinical studies.
B) Regression of atherosclerosis has yet to be observed in clinical studies.
C) Progression of atherosclerosis begins at puberty.
D) The rate of progression or regression between those who undergo usual medical care is no different from that in those who aggressively control risk factors.