it's D but I might be wrong
 
        
                    
             
        
        
        
Answer:
Theory: <u>A theory is a carefully thought-out explanation for observations of the natural world that has been constructed using the scientific method, and which brings together many facts and hypotheses.</u>
 
        
             
        
        
        
Answer:
The correct answer will be- arteries→capillaries→veins
Explanation:
The circulation of blood in the closed circulatory system flows through blood vessels. These blood vessels show structural differences in response to the pressure exerted by the blood on the surrounding medium.
The blood pressure varies in the circulatory system because the heart pumps the blood with a greater force, so the blood vessel called arteries which carries the blood from the heart posses thicker walls.
The blood pressure reduces until the blood reaches the organs, the blood pressure reduces. Thus the blood in the capillaries has lower pressure.
When blood exits from the organs back to the heart, then the blood pressure is highly reduced as a result, the veins carry the blood with lower pressure.
Thus, arteries→capillaries→veins are the correct answer.
 
        
             
        
        
        
The Crossing Over only occurs in the meiosis on prophase I and metaphase I
        
                    
             
        
        
        
Answer: b. can lead to other cardiovascular diseases
 
Explanation:
High blood pressure or hypertention can be define as a condition in which the flowing blood exerts force over the walls of the arteries. The arteries are the type of blood vessels which carries the blood from the heart to the rest of the body parts. This condition results in heart diseases like heart stroke or heart attack due to abnormal blood flow.