The correct answer is option 'D' i.e., retention of water and prevention of soil erosion.

Explanation:
Forests are essential for the survival of life on earth. They are responsible for various ecological, environmental, and social benefits. Forests play a crucial role in controlling drought by retaining water and preventing soil erosion. Let's discuss how forests control drought through water retention and soil erosion prevention:

Retention of water:

Forests help in retaining water in the following ways:

1. Watershed: Forests act as a water catchment area and function as a natural watershed. They store and release water gradually, reducing the risk of floods and droughts.

2. Groundwater recharge: Forests help in recharging groundwater by allowing rainwater to seep into the soil, thus replenishing underground water resources.

3. Transpiration: Trees in the forest transpire water, which helps in the formation of clouds and precipitation, leading to increased rainfall.

Prevention of soil erosion:

Forests help in preventing soil erosion in the following ways:

1. Root systems: Trees in the forest have deep root systems that hold the soil in place and prevent it from eroding.

2. Canopy cover: The canopy cover of trees in the forest acts as a barrier, reducing the impact of raindrops on the soil surface and preventing soil erosion.

3. Organic matter: Forests are rich in organic matter, which helps in improving soil structure, reducing soil erosion, and retaining water.

Conclusion:

Forests play a crucial role in controlling drought by retaining water and preventing soil erosion. Therefore, it is important to conserve and protect forests to ensure a sustainable future for all.