Degradation of PIFs occurs mainly in the presence of:
Correct option is B, Red light. In PSS-Sec-E-Sensory biology problems like this, the accurate statement is Red light; the others are common mix-ups. Not these: A) Darkness; C) Blue light; D) Far-red light. Tissue transport questions usually turn on xylem vs phloem, living vs dead cells, or source vs sink.
Ref: Best CSIR NET Plant Physiology books: Master Unit 6 with Taiz & Zeiger and Salisbury & Ross. Crack Part C experimental questions with top textbooks.