Answer:
The answer would be the last one, he is examining the physical characteristics. Why this is correct is because physical characteristics are visible to the naked eye and therefore everything he stated was just that, including color and shape/design
Explanation:
 
        
             
        
        
        
I believe this would be true
        
                    
             
        
        
        
Answer:
A- A pH change can cause the enzyme to change its shape
Explanation:
A rise or fall in the pH of the medium from the optimum of pH 7 usually affect  the  enzymes' active sites  of  and therefore the  shape and  the  rate of enzyme activity.
Assuming  the pH is too low, the enzyme medium becomes acidic;Acidosis. The high Hydrogen ions concentration  interacts with the R-groups of the amino acids moiety of the enzymes, this interaction affects the ionization of the  R-groups, disrupting the ionic bonding holding these R-groups in shape. 
This results in loss of the 3-Dimensional shape arrangements of the protein molecule  and therefore of the active sites. Since active sites of  enzymes  determines the specificity of the <u>enzymes substrate- complex </u> to give <u>enzyme-product complex,</u> the catalytic activity of the enzymes decreases, <u>the rate of  reaction decreases,and products formation stops, and the reaction also stops.</u>
The same is applicable to extremely high pH=Alkalosis.
 However, the effective buffer system of the body prevents this scenarios from happening in real sense in the body. Through mopping by the  haemoglobin, excretion by the kidney, etc