Phototropins belong to which light perception range?
Blue light (320–500 nm) (C) is correct here. This is core Phototropin+All: once you know the definition or pathway step, Blue light (320–500 nm) is the clear fit. The wrong ones are A) UV-B; B) UV-A; D) Far-red. 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.