Simon plots a cycling route on a map. Each unit represents one kilometer. What is the total length, in kilometers, of the route?
a) The length of the route depends on the scale of the map.
b) The length of the route is represented by the total number of units plotted.
c) The length of the route is determined by the number of kilometers Simon intends to cycle.
d) The length of the route is calculated by measuring the distance between the plotted points on the map.