The high protein (A) content of various strains of alfalfa plants, along with the (B) characteristically long root system that enables them to survive long droughts, (C) make them (D) particu

The high protein (A) content of various strains of alfalfa plants, along with the (B) characteristically long root system that enables them to survive long droughts, (C) make them (D) particularly valuable in arid countries