Ontario Grade 9 Science Class Practice Exam

A durable ecosystem is one that is able to withstand various pressures and disturbances such as climate changes, natural disasters, and human activities. While all of the other options may contribute to the resilience of an ecosystem, B is the most important factor as it ensures the continued survival of the ecosystem despite external challenges. A, supporting a large population, may put strain on the ecosystem and make it less resilient. C, creating energy, is important for the functioning of the ecosystem but does not necessarily make it more durable. D, reducing pollution, is important for the health of the ecosystem, but does not necessarily contribute to its durability. Therefore, B is the best answer as it encompasses the ability of an ecosystem to maintain itself in the face of various stressors.