Semi‑dwarf rice gene Sd‑1 affects synthesis of:
That points to B: Gibberellin. Compared with the other options, Gibberellin is the one that correctly describes the Phytohormone ALL concept. The wrong ones are A) Auxin; C) Cytokinin; D) ABA. If you’re stuck, eliminate anything that contradicts a basic fact you already know for this topic.
Ref: Best CSIR NET Plant Physiology books: Master Unit 6 with Taiz & Zeiger and Salisbury & Ross. Crack Part C experimental questions with top textbooks.