PhyB is most strongly associated with regulation of:
Pick B: Shade avoidance. Thinking through PHYTOCHROME step by step rules out the lookalikes and leaves Shade avoidance. Skip these: A) Seed germination; C) Vernalization; D) Stomatal movement. For hormones and genes, match the molecule or gene to its real role, not a neighboring pathway.
Ref: Best CSIR NET Plant Physiology books: Master Unit 6 with Taiz & Zeiger and Salisbury & Ross. Crack Part C experimental questions with top textbooks.