Which fungicide revealed the role of BRs in maize dwarf mutants?
Propiconazole (B) is correct here. This is core Brassinosteriod: once you know the definition or pathway step, Propiconazole is the clear fit. The wrong ones are A) Glyphosate; C) Paclobutrazol; D) AMO-1618. If the topic is about gradients or potentials, water/solutes move from higher to lower of the relevant quantity.
Ref: Best CSIR NET Plant Physiology books: Master Unit 6 with Taiz & Zeiger and Salisbury & Ross. Crack Part C experimental questions with top textbooks.