<prompt> Objective of ETDRS study isEffect of aspirin on the course of diabetic retinopathyTo observe patients with severe DR in type 1 and type 2 diabetes over 2 years to determine visual outcomesTo evaluate whether photocagulation prevents severe visual loss in eyes with diabetic retinopathyALL of the above  <response>: Option A - ETDRS studyOption C - DRS studyOption B - DRVS study 