According to the cell theory, which structure contains cells? a)blood b)water c)carbon dioxide d)chromosome

The correct answer is option A, that is, blood.  

Cell theory in biology refers to the universally acknowledged scientific theory that living species are constructed of cells, that is, they are the basic fundamental and structural unit of all species, and that all the cells arises from the pre-existing cells. The theory is credited to Schwann and Schleiden. The three postulates of the theory are:  

1. All living species comprises of one or more cells.  

2. Cell originate from the pre-existing cells.  

3. The cells is the fundamental unit of organization and composition in organisms.  

they are c. hope this !