OG的一道题

39. 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

答案是C. 能否请牛牛分析一下？A能不能算是同位语从句讲？