The correct answer is A. Control on Overgrazing.
Overgrazing is the excessive use of grazing land by livestock. It can lead to a number of problems, including soil erosion, loss of vegetation, and water pollution. Control on overgrazing is an important measure for soil conservation because it helps to prevent these problems.
Linear plantation is the planting of trees or shrubs in a line. It can be used to prevent soil erosion and to provide a barrier against wind and water. However, it is not an effective measure for soil conservation in all areas. For example, it is not effective in areas with high rainfall or in areas with steep slopes.
Construction of dams is a measure that can be used to control flooding and to provide water for irrigation. However, it is not an effective measure for soil conservation. Dams can actually contribute to soil erosion by creating a reservoir that can hold water for long periods of time. This can lead to the formation of deep pools of water, which can erode the soil around the dam.
In conclusion, the correct answer is A. Control on Overgrazing.