Wholesale price-based inflation rose to 8.56 per cent in January. Overall inflation in December last year was 7.31 per cent. The rise in inflation was driven by increased prices of food items such as sugar, potatoes and pulses.Sugar prices rose by 58.96 per cent in January year-on-year while potatoes turned costlier by 53.39 per cent and pulses by 45.64 per cent. On monthly basis, prices of masur increased by 9 per cent, arhar by 6 per cent and wheat by 4 per cent.Fuel index rose by 1.8 per cent due to higher prices of naphtha that rose 21 per cent. Furnace oil rose 6 per cent while bitumen, non-coking coal and light diesel oil rose 3 per cent each.