According to the classic study by de Wit et al.(1966),soybeans were grown in mixtures with a grass.Mixtures either received mineral nitrogen,were inoculated with Rhizobium,or both.The results of this experiment showed what?

A) Where environments are deficient in nitrogen, plants that are not nodulated legumes will outcompete nodulated legumes.
B) When the two species compete in fertilized soil, the grass outcompetes and produces a greater yield than the soybeans, regardless of whether Rhizobium were present. But, when nitrogen is deficient and Rhizobium are present the soybeans have a greater yield and it appears the grass will eventually be outcompeted.
C) Rhizobium have no effect on the yield of the plants because nitrogen availability is the single most important factor
D) When the two species compete in unfertilized soil, the grass outcompetes the soybeans and produces a greater yield, regardless of whether Rhizobium were present. But, when nitrogen is abundant and Rhizobium are present the soybeans have a greater yield and outcompete the grass.