GMAT Sentence Correction (SC) | Re: More by accident than design, scientific field studies in recent ye

More by accident than design,scientific field studies in recent years have begun to document the existence of very large flakes with laser probes that can make precise measurements.

(A) scientific field studies in recent years have begun to document the existence
(B) in recent years scientific field studies have begun to document the existence
(C) scientific field studies have begun to document the existence in recent years
(D) scientific field studies have begun in recent years to document