Which country among those listed has a population under 40 million?

Canada is the correct choice because its population is estimated to be just under 40 million. This places it in a distinct demographic category compared to the other countries listed. Germany, for instance, has a population exceeding 80 million, making it one of the most populous nations in Europe. Japan also has a significant population, exceeding 120 million, and is one of the most densely populated countries in the world. Russia, despite being the largest country by land area, has a population of approximately 146 million. Therefore, among the options provided, only Canada fits the criterion of having a population under 40 million.