Please choose the correct ending to complete the given sentence: Education and Communications: [header] How to build a self sustaining ecosystem [title] Choose a size for your ecosystem. [step] If you are new to building ecosystems, you may want to start small. However, the smaller your container, the harder it is to maintain a self-sustaining environment.

Ending1: Subtract, or add sizes of ecosystems, trees, flowers, plants, and other organisms. Purchase your selection online so you know what will fill the bottom. Ending2: Experiment with sizes and sizes until you find what works for you. [substeps] For example, a 10-gallon bucket won't take up a lot of room in a 2-gallon bucket. Ending3: Deciding on a size can require you to assess whether you want to work with plants, birds, insects, or other creatures in your ecosystem. [substeps] For example, a 10-gallon tank might require an aquarium pond 4-6 gallons. Ending4: Larger containers allow for the inclusion of multiple diverse species and give everything room to grow. All containers must be clear to let in light.

Answer format: ending1/ending2/ending3/ending4