7. Why is a cell considered as the basic structural and functional unit of all organisms? It is because of the _____________.
A. organelles which are capable to carry out metabolic activities
B. oxygen and hydrogen atoms which are combined to make the water molecule(H2O)
C. cells ability to generate heat which enables the organisms to whithstand cold temperature
D.carbon atom which readily bond with four other elements to form complex macromolecules of life