Final answer:
In a flower, the calyx and gynoecium are whorls, as are the corolla and stamen. Therefore, option D, 'A and B are all whorls,' is correct as both the calyx and gynoecium and the corolla and stamen are all whorls in a flower.
Step-by-step explanation:
The calyx and gynoecium are whorls in a flower. The calyx is the outermost whorl and consists of sepals that help protect the unopened bud, while the gynoecium is the innermost whorl and contains the female reproductive structures. Therefore, option A, 'Calyx and gynoecium,' is not a correct answer since both of them are whorls in a flower.
On the other hand, the corolla and stamen are also whorls in a flower. The corolla is the second whorl and consists of petals, usually brightly colored to attract pollinators. The stamen is the third whorl and contains the male reproductive structures. Therefore, option B, 'Corolla and stamen,' is not a correct answer since both of them are also whorls in a flower.
Option C, 'All of the above,' is not a correct answer because both options A and B are whorls in a flower. The correct answer is option D, 'A and B are all whorls,' as both the calyx and gynoecium and the corolla and stamen are all whorls in a flower.