This question checks whether you know the rough scale of the four terms that make up India's yearly water account: how much rain falls, how much evaporates or transpires, how much runs off into rivers, and how much quietly recharges groundwater.
- Potential flow in rivers > Precipitation > Natural recharge > Evapotranspiration: wrong, river flow is only ever a portion of total rainfall, so it can never be bigger than precipitation itself.
- Precipitation > Evapotranspiration > Potential flow in rivers > Natural recharge: correct, this matches the accepted national figures of about 4000 BCM rainfall, about 2131 BCM evapotranspiration, about 1869 BCM river runoff and about 432 BCM groundwater recharge.
- Potential flow in rivers > Precipitation > Evapotranspiration > Natural recharge: wrong for the same reason as the first choice, river flow cannot outrank precipitation.
- Precipitation > Potential flow in rivers > Evapotranspiration > Natural recharge: close, but it ranks river flow above evapotranspiration, while the real figures show India loses more water to evapotranspiration than to river runoff.
Ranking the four terms by their approximate national totals gives precipitation first, evapotranspiration second, potential flow in rivers third, and natural recharge last.
Let's summarize:
- Precipitation is always the largest term, since everything else is a fraction of it.
- Evapotranspiration outweighs river runoff in India's water budget, and natural groundwater recharge is the smallest share of all.
So the correct decreasing order is precipitation, evapotranspiration, potential flow in rivers, natural recharge, which is option 2.