Which of these is the fibre obtained from the coconut’s husk

The correct option is Coir.

To understand why this is correct, let's look at what each of the given options represents:
1. Coir: This is a natural fibre extracted from the outer husk of coconuts. The fibrous husk is processed to remove the tough fibres, which are then used to make products like ropes, mats, brushes, and growing mediums for gardening.
2. Perlite: This is an amorphous volcanic glass that has a relatively high water content. It is typically expanded by heating and is used as a soil amendment.
3. Vermiculture: This is not a fibre, but rather the practice of breeding and raising earthworms to decompose organic waste into nutrient-rich compost (vermicompost).
4. Rockwool: Also known as stone wool, this is a man-made mineral fibre made by spinning molten rock and minerals, commonly used for insulation and hydroponics.

Therefore, the fibre obtained from the coconut's husk is indeed Coir.