Answer:
The correct answer will be option-D.
Explanation:
Calcium plays an important role in muscle contraction as they are released from the sarcoplasmic reticulum after they receive electric impulse.
Calcium triggers the muscle contraction cycle as these calcium ions bind to the troponin-tropomyosin complex. This binding exposes the myosin-binding site on the actin on which high energy myosin binds and cross-bridge is formed.
This cross-bridge formation causes the contraction of the sarcomere and therefore muscle contracts.
Thus, option-D is the correct answer.
 
        
             
        
        
        
C: from what I can see in the graph
        
             
        
        
        
Answer: Image result for How are plant and animal cells different? What organelles do animal cells have that plant cells do not have? What organelles do plant cells have that animal cells do not have?
Animal cells have centrosomes and lysosomes, whereas plant cells do not. Plant cells
Explanation:
 
        
                    
             
        
        
        
Most of the water is salt water
        
                    
             
        
        
        
Translation occurs in the nucleus to produce a pre-mRNA molecule.  The pre-mRNA is the processed into the mature mRNA which exists the nucleus and is translated into the cytoplasm.
So, the answer is B)  NUCLEUS