The correct answer is option 4: all living and non-living things in an area. An ecosystem is a complex system that includes both the living (biotic) and non-living (abiotic) components in a specific area.

Option 1, which states that an ecosystem comprises only trees, shrubs, and herbs, is incorrect. While plants are an important part of an ecosystem, they do not represent the entire system.

Option 2, which suggests that an ecosystem comprises only animals, is also incorrect. Animals are an integral part of an ecosystem, but they are not the sole components that make up the system.

Option 3 states that an ecosystem comprises all plants and animals in an area. While this is partially true, it is important to note that an ecosystem includes more than just plants and animals. It also encompasses non-living factors such as air, water, sunlight, soil, and minerals.

The correct answer, option 4, acknowledges that an ecosystem consists of all living (plants and animals) and non-living (air, water, soil, etc.) things in a specific area. These components interact and depend on each other, creating a delicate balance within the ecosystem.