Please Use the Following Information to Answer the Question(s) Below

Multiple Choice

Please use the following information to answer the question(s) below.
A scientist conducts an experiment to quantify the effect of mycorrhizae and soil nitrogen levels on plant growth in a grassland. The experiment has four treatments: (1) Mycorrhizae present and ambient levels of nitrogen, (2) mycorrhizae present and nitrogen added, (3) mycorrhizae absent and ambient levels of nitrogen, and (3) mycorrhizae absent and nitrogen added. After four weeks, the scientist removes the aboveground plant material for weighing. Figure 42.4.
-What conclusion is best supported by Figure 42.4?

A) In the ambient condition, plants are limited by nitrogen even when mycorrhizae are present.
B) Interactions with mycorrhizae allow for the highest primary production levels regardless of nitrogen level.
C) Interactions with mycorrhizae are always mutualistic.
D) Mycorrhizae should be added to restore successfully grasslands with high soil nitrogen.