The process of breeding of selective parents for obtaining special characters in their offspring such as soft under hair in sheep, is termed as selective breeding.

The maximum length of continuous silk thread that can be obtained from a cocoon is more than that of 1000 feet (1000 to 1500 feet) continuous in length.

Silk and wool are two fibres which are made up of proteins.

In Tibet and Ladakh, angora goats are found.

Wool yielding animals are sheep, yak, llama, alpaca, angora goat, angora rabbit and camel.

The most common silk moth is the mulberry silk moth. The silk obtained from the Cocoons of mulberry silk moth is called mulberry silk. Mulberry silk is soft, lustrous (shiny) and elastic and can be dyed in different colours.

There are following two types of fibres that form the hair to sheep
(i) The coarse beard hair.
(ii) Fine soft under hair close to the skin

A pile of cocoon is used for obtaining silk fibre. The Cocoon are kept under the sun, boiled water or exposed to steam. The silk fibres separate out. The process of taking, out threads from the Cocoon for use as silk is called reeling the silk.

According to an old Chinese legend, the empress Si-Iung-Chi was asked by the emperor Huang-ti to find the cause of the damaged leaves of mulberry trees growing in their garden. The empress found white worms eating up mulberry leaves. She also noticed that they were spinning shiny cocoons around them. Accidentally, a cocoon dropped into her cup of tea and a tangle of delicate threads separated from the cocoon. This is how silk was discovered by chance. In this way, the first silk industry began in China.

Natural silk is obtained from the cocoons of silkworms and it is made up of a protein. Natural silk is an animal fibre. Artificial silk is obtained from wood pulp and it is made up of modified plant material 'cellulose.
If we perform the burning test, then natural silk fibre burns giving a smell of burning hair while artificial fibre burns giving a smell of burning paper.

(a) Neha's mother took a thread of natural silk fabric and another thread of artificial silk fabric and burn them separately. The thread which burns giving a smell of burning hair will be natural silk (or pure silk). The thread which burns giving a smell a burning paper will be an artificial silk.
(b) Yes, pure silk saree is more costly than an artificial one.
(c) Neha's mother is intelligent and knowledgeable.