A potential source of nitrogen in a sandy soil environment might be the bacterium, Rhizobium, which inhabits the root nodules of
leguminous plants. Which of these statements is true, and should prevent Rhizobium or other root-inhabiting nitrogen-fixers from contributing nitrogen to the soils for bryophytes? A) Mosses evolved before there were substantial amounts of nitrogen in Earth's atmosphere.
B) Mosses have no roots.
C) Moss gametophytes lack stomata.
D) Among land plants, only legumes are known to establish symbiotic relationships with members of other kingdoms.
