Final answer:
An ecosystem is a system of interconnected living organisms and their physical environment. Lake Erie and everything living in it is an example of an ecosystem, as it is a freshwater lake that supports a variety of organisms in different habitats.
Step-by-step explanation:
An ecosystem is a system of interconnected living organisms and the physical environment in which they interact. It can be as small as a pond or as large as a forest or continent. Freshwater ecosystems include lakes, rivers, streams, and springs, and they are quite diverse, supporting a variety of animals, plants, fungi, protists, and prokaryotes.
Lakes and ponds, which can range in size, are examples of freshwater ecosystems. They have different zones, such as the photic zone where light can penetrate and phytoplankton carry out photosynthesis, and the aphotic zone where bacteria break down dead organisms. These ecosystems play important roles in providing resources for humans and sustaining a food web.
Therefore, answer option 1) Lake Erie and everything living in it is an example of an ecosystem because it is a freshwater lake that supports a variety of organisms in different habitats.