Answer:
Veins.
Explanation:
Heart is the main organs of circulatory system that transport blood in the body.Human heart is four chambered and separates the oxygenated and deoxygenated blood in the body.  
Arteries are responsible for the passage of blood from heart to the body parts. The deoxygenated blood from the body collect in the veins and transfer to heart. Arteries has high pressure than veins and veins are thinner than artery.
Thus, the answer is veins. 
 
        
             
        
        
        
By polishing it, it becomes more clear which becomes so Clear that you could see your reflection.
        
             
        
        
        
Organisms that reproduce sexually have greater genetic and thus characteristic variations, and so, are able to withstand more selection pressures if they so happen to change or become greater. This increases the chances of survival for that species itself.
Organisms that reproduce asexually are genetically identical to each other. They are unlikely to withstand any changes in selection pressures.
Hope this helps! :)
        
             
        
        
        
Answer: Lk for this plasmid = 47 
Explanation:
The formula to compute Lk is given by :-
Topological Linking Number (Lk): Twist (Tw) + Writhe (Wr)
Given: A plasmid 41 twists and 6 right handed writhes. 
i.e. Twist (Tw) = 41   , Writhe (Wr) = 6
Then, Topological Linking Number (Lk) for this plasmid :  = 41+6
= 47
Hence, the Lk for this plasmid = 47