In basic materials science and general science, which of the following fibres is a fully man made or synthetic fibre produced from petrochemicals rather than obtained directly from plants or animals?

Introduction / Context:
Fibres used in textiles and other products can be broadly classified into natural fibres and man made or synthetic fibres. Natural fibres are obtained from plants and animals, while synthetic fibres are produced through chemical processes, usually starting from petroleum based raw materials. Knowing which fibres belong to which category is a common topic in school level science and competitive exams. This question asks you to pick the man made fibre from a list of common examples.

Given Data / Assumptions:
- The question specifically mentions “man made fibre.”
- The options are cotton, wool, silk, and nylon.
- Cotton comes from plants; wool and silk come from animals; nylon is industrially manufactured.
- We assume standard textbook information about fibre sources and classification.

Concept / Approach:
Cotton is a natural cellulose fibre obtained from the seed hair of the cotton plant. Wool is a natural protein fibre obtained from the fleece of sheep and certain other animals. Silk is also a natural protein fibre, produced by silkworms when spinning their cocoons. Nylon, on the other hand, is one of the first fully synthetic fibres developed by chemists. It is produced from petrochemical monomers through polymerisation reactions in factories. Nylon does not occur in nature and is therefore classified as a man made or synthetic fibre. Among the options, only nylon fits the description of a fully man made fibre.

Step-by-Step Solution:
Step 1: Separate the options into plant based, animal based, and synthetic categories. Step 2: Identify cotton as plant based, coming from cotton plants. Step 3: Recognise wool and silk as animal based fibres: wool from sheep and silk from silkworms. Step 4: Recall that nylon is made in factories from petrochemicals through chemical synthesis. Step 5: Conclude that nylon is the only man made fibre in the given list.

Verification / Alternative check:
Science textbooks often classify fibres into natural (cotton, jute, wool, silk) and synthetic (nylon, polyester, acrylic). They explain that nylon was developed to replace silk in some applications and is produced by combining chemicals derived from coal, air, and water, now mainly petroleum. They also describe properties such as strength, elasticity, and resistance to wrinkles for synthetic fibres. Because cotton, wool, and silk are always listed under natural fibres, and nylon is always listed under synthetic fibres, the classification is unambiguous.

Why Other Options Are Wrong:
Cotton, a natural cellulose fibre obtained from plants, is not chemically manufactured and thus is not a man made fibre.
Wool, a natural protein fibre from animals like sheep and goats, grows on animal bodies and is not synthesised in factories.
Silk, a natural protein fibre produced by silkworms, is harvested from cocoons and is not created from petrochemicals.

Common Pitfalls:
Students sometimes confuse “artificial” and “synthetic” with “processed.” While cotton cloth is manufactured, the fibre itself is natural. The same is true for woollen and silk fabrics. The key is to ask whether the fibre originally comes from a living organism or is synthesised by chemical reactions from non biological raw materials. If it is produced in laboratories or factories from petroleum based chemicals, it is a synthetic fibre. Remembering that nylon, polyester, and acrylic are classic examples of synthetic fibres will help you answer such questions quickly.

Final Answer:
The man made or synthetic fibre in the list is Nylon, a synthetic fibre manufactured from petrochemical products.