The `graded profile` of a river course refers to the smooth curve formed by the river from its source to its mouth. It represents the ideal equilibrium between erosion and deposition along the river`s course. Option 1 correctly states that the graded profile is a smooth curve from source to mouth. This means that the river`s gradient gradually decreases as it flows downstream, resulting in a gentler slope. It is important to note that the graded profile can be affected by various factors such as the type of rock and sediment present, tectonic activity, and human interference. These factors can cause deviations from the ideal graded profile. Therefore, although option 1 is generally correct, it is important to consider the influences that may alter the smoothness of the curve.