The correct option is B. A water shed refers to an area of land which serves as channel for rainfall and supply other bodies of water connected with it with water. The amount of water in the watershed determines the quantity of water that will be passed to the water bodies that are connected to the watershed. A model is usually made in order to use it to forecast or predict a certain thing. A watershed model can be used to predict the amount of floods and drought at a particular location.<span />
