Explanation:

Compacted density:
Compacted density refers to the density of soil after it has been compacted. It is an important parameter in geotechnical engineering as it affects the strength, stability, and permeability of the soil.

Water content of soil:
Water content of soil refers to the amount of water present in the soil. It is expressed as a percentage of the weight of the water to the weight of the dry soil.

Effect of water content on compacted density:
The compacted density of soil is influenced by its water content. The relationship between water content and compacted density can be explained as follows:

1. Increased water content:
When the water content of the soil is increased, the particles of the soil become more lubricated and can slide more easily past each other. This results in a decrease in the interparticle friction and an increase in the soil's ability to be compacted. As a result, the soil particles can be packed closer together, leading to an increase in the compacted density.

2. Decreased water content:
On the other hand, when the water content of the soil is decreased, the particles of the soil become less lubricated and have a higher interparticle friction. This makes it more difficult to compact the soil and the particles cannot be packed as closely together. Therefore, the compacted density decreases.

3. Constant water content:
If the water content of the soil remains constant, the compacted density will also remain constant, assuming all other factors remain the same.

Conclusion:
In conclusion, the compacted density is increased when the water content of the soil is increased. This is because the increased water content reduces the interparticle friction and allows the soil particles to be packed closer together, resulting in a higher compacted density. Therefore, option 'A' is the correct answer.