The correct answer is C. Both (A) and (B).
The shape of the recession limb of a hydrograph depends on the basin characteristics and the storm characteristics. The basin characteristics include the size of the basin, the shape of the basin, the land use in the basin, and the soil type in the basin. The storm characteristics include the intensity of the storm, the duration of the storm, and the antecedent moisture conditions.
The basin characteristics affect the shape of the recession limb by controlling the rate at which water flows out of the basin. The larger the basin, the slower the water will flow out of the basin. The shape of the basin also affects the rate at which water flows out of the basin. A basin with a steep slope will have a faster recession limb than a basin with a gentle slope. The land use in the basin also affects the rate at which water flows out of the basin. A basin with a lot of impervious surfaces, such as roads and parking lots, will have a faster recession limb than a basin with a lot of pervious surfaces, such as forests and grasslands. The soil type in the basin also affects the rate at which water flows out of the basin. A basin with a lot of clay will have a slower recession limb than a basin with a lot of sand.
The storm characteristics affect the shape of the recession limb by controlling the amount of water that falls on the basin. The more intense the storm, the more water will fall on the basin. The longer the storm, the more water will fall on the basin. The antecedent moisture conditions also affect the shape of the recession limb. If the basin is already wet, the recession limb will be slower than if the basin is dry.
The shape of the recession limb is important because it can be used to predict the amount of water that will flow out of the basin. This information can be used to manage floods and droughts.