What is the result that would most strongly refute their hypothesis? [hypothesis: sugars made by one plant during photosynthesis can travel through a mycorrhizal fungus and be incorporated into the tissues of another plant.]a) no movement: carbon-14 is found in the birch seedling's tissues and carbon-13 in the douglas fir. b) reciprocal exchange: carbon-14 is found in the douglas fir seedling's tissues and carbon-13 in the birch. c) either carbon-13 or carbon-14 is found in the fungal tissues. d) either carbon-13 or carbon-14 is found in the cedar seedling's tissues.