Brandon drew 4 circles, each with a different diameter, on a piece of paper. For each circle, he laid a piece of string along the outline and then measured the length of the string. His results are shown in the table below. Circle Measurements Diameter Length of String 5 cm 15.7 cm 10 cm 31.4 cm 15 cm 47.1 cm 20 cm 62.8 cm Brandon wrote the equation, y = kx, to model the relationship between the circumference, y, and the diameter, x, of the circle. Which of the following statements correctly describe what k represents in this equation? k represents the radius k represents the unit rate k represents the area k represents