The correct option is D Promotion of untouchability.
Hindu-Muslim unity was established during the Non-Cooperation Movement. People lit public bonfires of foreign clothes and goods and promoted Indian (Swadeshi) goods. Thus, the imports of foreign clothes and other goods fell drastically; the market for Indian goods started to grow. People contributed one crore rupees to the ‘Tilak Swarajya Fund’. Social issues like untouchability and its prohibition were also discussed.