A food chain involving Spartina (a plant), the marsh periwinkle snail, the blue crab and an unknown fungus was identifie
a food chain involving spartina (a plant), operates via +and+ represents established outcome. functional assays validates option D. Other options propose substrate or regulatory direction, inconsistent with published kinetics and mutant phenotypes.
Ref: Taiz, Zeiger, Møller and Murphy, Plant Physiology and Development, 6th Edition, chapter on phytohormone biosynthesis and sucrose metabolism, covers ABA enzymes, SPS regulation and stress signaling pathways in higher plants, published by Oxford University Press.