I think observation and measurable.
        
             
        
        
        
B) cod is the answer im sure
        
                    
             
        
        
        
A cell would have 46 chromosomes during metaphase I.
        
             
        
        
        
Answer: The virus weakens as time passes.
Explanation:  The virus will weaken continuously during transmission, and  will reduce its toxicity after several generations of transmission, without causing much harm to the human body.