CIB1 regulates flowering by binding to promoter of:
FT (C) is correct here. This is core cryptochrome: once you know the definition or pathway step, FT is the clear fit. The wrong ones are A) AP1; B) LFY; 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.