Which one of the following is the smallest unit showing the properties

Which one of the following is the smallest unit showing the properties of life such as capacity for metabolism, response to the environment, growth and reproduction ?

Gene
Chromosome
Nucleus
Cell
This question was previously asked in
UPSC NDA-1 – 2015
The cell is considered the fundamental structural and functional unit of life. It is the smallest unit that exhibits all the basic properties of life, including metabolism, response to stimuli, growth, and reproduction (at the cellular level, via division). Genes, chromosomes, and the nucleus are components within a cell and cannot independently perform all life processes.
Understanding the concept of the cell as the basic unit of life.
Genes are units of heredity made of DNA. Chromosomes are structures containing coiled DNA, carrying genetic information. The nucleus is an organelle containing the cell’s genetic material in eukaryotes. All these components work within the framework of a cell to carry out life functions.