Which photoreceptor perceives day length and circadian rhythms?
Correct option is C, Zeitlupe. In PSS-Sec-E-Sensory biology problems like this, the accurate statement is Zeitlupe; the others are common mix-ups. Not these: A) Cryptochrome; B) Phototropin; D) UVR8. 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.