Indigo cultivation in India declined by the beginning of the $20^{\text{th}}$ century because of

Answer: B. Indigo cultivation in India declined by the early 20th century mainly because of UNPROFITABILITY IN THE WORLD MARKET DUE TO NEW INVENTIONS (synthetic dyes). INDIGO HAD BEEN A MAJOR CASH CROP in colonial India from the late 18th century, with significant cultivation in Bengal (especially Champaran, Bihar; lower Bengal), and southern India. The dye was a leading raw material for the British and European textile industry, since natural indigo was the principal source of fast blue colour for cloth. The DECISIVE BLOW to natural indigo came from CHEMISTRY: 1. In 1878, the German chemist ADOLF VON BAEYER synthesised indigo in the laboratory. 2. By 1897 the German chemical firm BASF had commercialised SYNTHETIC INDIGO at scale. 3. Within a few years synthetic indigo had captured the world dye market, displacing natural indigo from India and other producers (Java, Central America). ECONOMIC IMPACT ON INDIA: 1. Natural indigo prices COLLAPSED in the 1890s and 1900s as synthetic supplies surged. 2. Indigo plantations in Bihar (Champaran), Bengal, and elsewhere became increasingly UNPROFITABLE. 3. The acreage under indigo CONTRACTED steeply. By around 1910 to 1917 natural indigo had been largely displaced. 4. There was a brief revival during WORLD WAR I (1914 to 1918) when German synthetic indigo supplies to Britain were cut off, but this was short-lived. CHAMPARAN SATYAGRAHA (1917), Gandhi's first major mass campaign in India, addressed the residual TINKATHIA system under which Bihar's planters had still been coercing peasants to grow indigo on 3/20 of their land, despite the falling market. The economic basis of indigo had collapsed by then; Gandhi's intervention abolished the lingering compulsion. Why other options are WRONG: (A) Peasant resistance (notably the INDIGO REVOLT OF 1859 to 1860 in Bengal) was significant in restricting the planters' coercive practices in lower Bengal, but it did not cause the WORLD-MARKET decline of indigo in the late 19th century. The chemistry of synthetic dyes was the decisive cause. (C) National leaders' opposition came after, and was a response to, the decline. It did not cause the decline. (D) Government control over planters: the colonial government did not significantly control planters; it had typically backed them. Source: NCERT Class 8 Our Pasts III; NCERT Class 12 Themes in Indian History Part III 'Colonialism and the Countryside'; Bipan Chandra et al. 'India's Struggle for Independence'.