Which gene directly acts as florigen in Arabidopsis?
FT (B) is correct here. This is core VERNALIZATION & FLOWERING: once you know the definition or pathway step, FT is the clear fit. The wrong ones are A) CO; C) FD; D) FLC. 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.