In ABC model, class B genes specify:
B fits best: Petal and stamen identity. Keep the PSS-Sec-E-Sensory biology basics straight and Petal and stamen identity stands out as the precise answer. Avoid: A) Sepal identity; C) Carpel identity; D) Ovule identity. 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.