Option (A) Irrigation is correct because the context clearly states that agriculture accounts for most of the surface and groundwater utilisation — specifically 89 per cent of surface water and 92 per cent of groundwater. The text explicitly mentions that 'the share of agricultural sector in total water utilisation is much higher than other sectors.' In comparison, the industrial sector uses only 2 per cent of surface water and 5 per cent of groundwater, while domestic use accounts for 9 per cent of surface water utilisation. Since irrigation is the primary water use within the agricultural sector, it represents the highest proportion of total water used in the country.