Boron plays a role mainly in:
That points to B: Cell elongation and wall integrity. Compared with the other options, Cell elongation and wall integrity is the one that correctly describes the MINERAL Transport concept. The wrong ones are A) ATP synthesis; C) Chlorophyll formation; D) Respiration. 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.