Based on the information provided in the graph, where the population increases drastically from 1800 to 1835 and then becomes constant at 1.5 million, it can be concluded that the carrying capacity of the environment for this species is approximately c. 1.5 million.
The graph depicting the population of a species from 1800 to 1925 suggests that the carrying capacity of the environment for this species is approximately 1.5 million individuals. The initial drastic increase in population from 1800 to 1835 indicates a period of rapid growth and colonization of available resources. However, after reaching around 1.5 million individuals, the population becomes constant, suggesting that the environment has a limited capacity to sustain the species. The stabilization of the population at 1.5 million implies a balance between birth rates and death rates, indicating that the environment has reached its carrying capacity—the maximum population size that the ecosystem can support over the long term without degradation. Therefore, the correct answer is (c) 1.5 million.