The study involved 1000 patients whose cardiac disease was not well controlled by existing medications-drugs such as ACE inhibitors and beta-blockers-and had suffered persistent symptoms that had been lasting for at least a year.

(A) and had suffered persistent symptoms that had been lasting for at least a year

(B) and suffered from persistent symptoms that had lasted for at least a year

(C) but were suffering from persistent symptoms that had been lasting for a year or more

(D) and who suffered persistent symptoms that had been lasting for at least a year

(E) but had suffered from persistent symptoms that lasted for a year or more

OA D

Source: Veritas Prep