The correct option is D Dots of different sizes cannot be used in the same map.
Dot maps are one of the three ways of demonstrating the distribution of variables over a particular region. A legend shows the data represented by each dot. The size of a dot remains uniform for the same data set. The thickness of dots can vary to depict the distribution of a heterogeneous variable in a dot map. Different thematic layers can be combined using different colours, shapes, and sizes.