The correct option is (b).
Explanation
The cotton boll is the fruit (capsule) of the cotton plant (genus Gossypium). It develops from the ovary of the flower and serves as a protective case for the seeds and the developing fibers.
Statement-wise Analysis:
- Statement 1 is Incorrect: The cotton boll is the fruit of the plant, located on the branches above ground. It is not the root.
- Statement 2 is Correct: Upon reaching maturity, the boll dries and bursts open (dehisces), exposing the white, fluffy fibers and the seeds they cover.
- Statement 3 is Incorrect: The fibers covering the seeds are cotton fibers, which are composed of cellulose. Silk fibers are protein-based filaments produced by silkworms. While cotton fibers may appear lustrous, they are chemically and biologically distinct from silk.
Key Takeaway:
The cotton boll is the mature fruit of the cotton plant that bursts to release cellulosic fibers. It is morphologically distinct from roots and chemically distinct from proteinaceous silk.