Which of the following groups contain only synthetic fibres?

The correct answer is option 3. PVC, Polythene, Bakelite.

Out of the following groups, only PVC, Polythene, and Bakelite contain only synthetic fibers:

Nylon, Terylene, Wool: Nylon and Terylene are synthetic fibers, but Wool is a natural fiber derived from sheep.

Cotton, Polycot, Rayon: Cotton is a natural fiber, while Polycot is a blend of cotton and polyester (synthetic) fibers, and Rayon is a semi-synthetic fiber made from cellulose (natural) but processed to alter its properties.

PVC, Polythene, Bakelite: All three - PVC (Polyvinyl Chloride), Polythene (Polyethylene), and Bakelite - are synthetic polymers.

Acrylic, Silk, Wool: Acrylic is a synthetic fiber, but Silk is a natural protein fiber produced by silkworms, and Wool, as mentioned earlier, is also a natural fiber.