The primary purpose of this essay is to inform reader about the significant stages of water cycle as described below.
1. Precipitation: rain, snow etc
2. Evaporation: evaporation of water vapour into the atmosphere due to hotness
3. Condensation: formation liquid droplets due to cooling from the vapor. This process is going to happen once the water vapour undergoes cooling.
Thus, the options (c), (b) and (a) are incorrect.
The primary purpose of this essay is to inform reader about the significant stages of water cycle.
Therefore, the correct option is – d. To inform the reader about the stages of the water cycle.