Answer :
The correct answer is a cell.
The basic life building block is the cell.
The cell is termed as the biological, functional and structural unit of every living organisms. They are referred to as building blocks.
Cell biology is the study of cell. Cytoplasm is being found in the cell which is enclosed in a membrane. The biomolecules which are contained in a cell include nucleic acids and proteins.
There are organisms which contains single cell for example, bacteria and those which are multicellular for example, animals and plants.