Which whorls are affected in agamous (AG) mutants?
That points to C: Stamens and carpels. Compared with the other options, Stamens and carpels is the one that correctly describes the ABC MODEL concept. The wrong ones are A) Sepals and petals; B) Petals and stamens; D) Sepals and carpels. If you’re stuck, eliminate anything that contradicts a basic fact you already know for this topic.
Ref: Best CSIR NET Plant Physiology books: Master Unit 6 with Taiz & Zeiger and Salisbury & Ross. Crack Part C experimental questions with top textbooks.