Concept:The basic functional and structural unit of life is the cell.
Explanation:In biology, cells are described as the building blocks of all living things.
Each cell can carry out essential life processes such as metabolism, energy production, and reproduction.
Higher levels of organisation depend on cells: tissues are groups of similar cells, organs are made of different tissues working together, and systems are groups of organs coordinated for specific functions.
Because tissues, organs, and systems are all composed of cells, they cannot be described as the basic unit of life.
The cell therefore qualifies as the smallest unit with the properties of life.
Answer:The correct answer is Option A — cell.