GMAT Sentence Correction (SC) | Re: For members of the seventeenth-century Ashanti nation in

For members of the seventeenth-century Ashanti nation in Africa, animal-hide shields with wooden frames were essential items of military equipment, a method to protect warriors against enemy arrows and spears.

A. a method to protect

B. as a method protecting

C. protecting

D. as a protection of

E. to protect

Not convinced with the old discussions on this, plz throw some light and concepts