Often, a Patient Does Not Show Signs and Symptoms of COPD

Often, a patient does not show signs and symptoms of COPD until they are over 40 years of age because

A) COPD is a result of the cumulative effects of smoking.
B) people do not visit the doctor on a regular basis until they are elderly.
C) pulmonary function tests are not administered on young people.
D) renal blood flow is maintained at a normal rate until age of 40.
E) other health problems can trigger the signs and symptoms of COPD.