Match the following options correctly:

(a)- ii, (b)- iv, (c)- iii, (d)- i

The introduction of canal irrigation has brought about a perceptible transformation in the agricultural economy of the region. Soil moisture has been a limiting factor in the successful growing of crops in this area. The Spread of canal irrigation has led to an increase in cultivated area and the intensity of cropping. The traditional crops sown in the area, gram, bajra and jowar have been replaced by wheat, cotton, groundnut and rice. This is the result of intensive irrigation.

The publication of ‘The Population Bomb’ by Ehrlich in 1968 and ‘The Limits to Growth’ by Meadows and others in 1972 further raised the level of fear among environmentalists in particular and people in general.