Is any functional structure within the confines of a cell; literally a. small organ; it usually has a membrane-based structure

Cell organelle

Explanation:

The cell organelle is the small organ-like structure present inside the cell in the cytoplasm.

Different types of cell organelles are present in the cell which performs specific functions like of storage, of digestion of biomolecules like lysosomes, of protein synthesis and many others.

The organelles are usually enclosed by either a single phospholipid membrane like in lysosomes, Golgi apparatus or two lipid layers like in nucleus and chloroplast.

Thus, cell organelle is the correct answer.

1. efficient use of space

2. elimination of groundwater contamination

3. energy generation

4. lower carbon footprint