PHOT1 primarily mediates phototropism under:
That points to C: Low and high blue light. Compared with the other options, Low and high blue light is the one that correctly describes the Phototropin+All concept. The wrong ones are A) Only low light; B) Only high light; D) Red light. 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.