I believe that the answer is: Most organisms are made up of one or more cells
Cell Theory was first developed in 1839 by Schleiden and Schwann, they stated that all organisms are composed of one or more cells.
Answer:
Answer is C.
Explanation:
A. The vessel length is pretty much constant. The body can't length or shorten blood vessels.
B. Blood viscosity is also fairly constant because the composition of blood cannot change quickly enough to change resistance as needed.
C. This is the main way resistance is controlled. The smooth muscle surrounding blood vessels can rapidly respond to hormonal or metabolic stimuli and contract/relax to adjust diameter.
D. Again, temperature is fairly constant in the body and would not be a good way to alter resistance.
Single or multi-celled structure, membrane-bound organelles, cell(s) larger than prokaryotes
The answer is C. A layer of rock or soil that holds water underground.