The correct answer is D) Raffia.
The material that would be best to use for binding the stems is Raffia.
Raffia is a species of palm. The palm has fibers in its leaves. This fiber is so good that the industry has used in the fabrication of nets, textiles, baskets, and hats. The material is very resistant.
So in the case of the bridesmaids’ bouquets, Raffia could be a great idea for binding the stems of the simple bouquet. It goes with the thematic of the wedding, that is going to be held outdoors in a farm, in a country barn, next to a hayfield. It really complements the colors of the wedding and the setting.