(a) Study Fig. 4.1 (Insert), which is a photograph of part of a river. [Figure 4.1 (Insert) is a photograph of a river. It shows a winding river channel with features labelled X and Y. X is likely a river cliff or cut bank on the outside bend, and Y is likely a slip-off slope or point bar on the inside bend.] (b) Study Fig. 4.2, which is a map of the delta of the Pearl River in China. [Figure 4.2 is a map of the Pearl River delta in China. It shows a network of numerous distributaries and channels flowing into Lingding Bay and the South China Sea. A scale bar indicates 30 km.]