‘Tinkathia System” in Champaran meant

The Tinkathia system was an exploitative indigo arrangement in Champaran (Bihar), where European planters forced raiyats to grow indigo on 3 out of every 20 kathas of their holding, which is 3/20 or 15 per cent of the land. Since a bigha was 20 kathas, 'tinkathia' literally means three katha per bigha. That makes option A correct.

Why the others fail:

• B (33%) confuses the term with a one-third share. No such standard ratio existed in the Champaran tenure.
• C (30%) is a doubling error. The system was 3/20, not 3/10.
• D (None) is wrong because A correctly states the ratio.

The core concept is colonial indigo cultivation and the tenancy grievances that led to the Champaran Satyagraha of 1917, the Indigo Commission of 1915-16 and the Champaran Agrarian Act of 1917, which ended the system. For Mains, it is a strong example of how commercial agrarian policy under colonial rule fed peasant unrest and shaped Gandhian mobilisation.

Trap: Aspirants try to convert 3/20 into a neat percentage and then pick the nearest-looking option. Know the fraction and its meaning, not just the percentage.