Dephosphorylation of phototropin in darkness is mediated by:
C fits best: Protein phosphatase 2A. Keep the Phototropin+All basics straight and Protein phosphatase 2A stands out as the precise answer. Avoid: A) Kinase; B) Proteasome; D) COP1. Light and flowering items often hinge on which photoreceptor or day-length rule is in play.
Ref: Best CSIR NET Plant Physiology books: Master Unit 6 with Taiz & Zeiger and Salisbury & Ross. Crack Part C experimental questions with top textbooks.