SEP1/SEP2/SEP3 triple mutants produce flowers with:
C fits best: Only sepals. Keep the ABCE & ABCDE MODEL +Synapdrgon flowering basics straight and Only sepals stands out as the precise answer. Avoid: A) All organs absent; B) Only stamens; D) Leaf-like structures. 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.