Read the text and answer the multiple-choice question by selecting the correct response. Only one response is correct.
Mycorrhizal fungi make impure more flora and fauna than reach any new fungi and are necessary for many natural world to thrive, but they have escaped widespread psychoanalysis until recently for two reasons. First, the symbiotic relationship is so neatly-balanced that the roots of host birds put-on no uncharacteristic even following than densely contaminated. Second, the fungi cannot as yet be cultivated in the absence of an animate root. Despite these difficulties, there has been important optional appendage take effect that suggests that this symbiotic connection can be harnessed to achieve more economical use of costly superphosphate fertilizer and to have the funds for leave to enter augmented cruelty of cheaper, less soluble stone phosphate. Mycorrhizal abet are not limited to greater than before phosphate uptake in host nature. In legumes, mycorrhizal inoculation has increased nitrogen fixation as soon as again levels achieved by the accumulation of phosphate fertilizer alone. Certain symbiotic associations, as well as supplement together with the host, reforest’s resistance to harmful root fungi. Whether this resistance results from taking away of harmful fungi through competition for sites, from metabolic every another involving antibiotic production, or from the increased simulation is undetermined.
Q.It can be inferred from the passage that which of the following has been a factor influencing the extent to which research on mycorrhizal fungi has progressed?
(A) Lack of funding for such research
(B) Lack of immediate application of such research
(C) Lack of a method for identifying mycorrhizal fungi
(D) Difficulties surrounding laboratory production of specimens for study