The correct option is (a).
Explanation
Jute is a natural fibre obtained from the stem of the jute plant (genus Corchorus). The quality of the fibre depends significantly on the timing of the harvest and the biological extraction process known as 'retting'.Statement 1 is Correct: The jute plant is normally harvested when it is at the flowering stage. If the plant is allowed to mature further to the seed-bearing stage, the fibre becomes coarse, hard, and lacks the characteristic lustre, thereby reducing its commercial quality.
Statement 2 is Incorrect: The harvested stems are not dried in the sun immediately. Instead, they are tied into bundles and immersed in stagnant water for several days. This process is called retting. During retting, bacteria decompose the gummy matter (pectin) that holds the fibres to the inner woody core, facilitating separation.
Statement 3 is Incorrect: After the stems have rotted sufficiently, the fibres are separated from the stalk primarily by hand (manual stripping). The statement that they are separated "exclusively by mechanical threshers" is false. Manual stripping is the dominant method in major jute-producing regions to ensure the fibres remain long and unbroken.
Key Takeaway: High-quality jute is harvested at the flowering stage and extracted through retting (microbial decomposition in water), followed by manual stripping of the fibre.