Answer:
by the sarcoplasmic reticulum's calcium ion pumps
Explanation:
Rigor mortis or postmortem rigidity, is a state caused by chemical changes in the muscles that occur post mortem and  cause the limbs of the corpse to stiffen.
This occurs because after death, there is no cellular respiration and consequently, no oxygen nor ATP (ATP is required for the muscle relaxation).
Calcium enters the cytosol after death because it is released due to the deterioration of the sarcoplasmic reticulum and due to the breakdown of the sarcolemma. Ca2+ ions activate the formation of actin-myosin cross-bridging necessary for the contraction. Muscles are unable to relax, because myosin heads continue to bind with the active sites of actin and there is no ATP to destabilize the myosin-actin bond.
 
        
             
        
        
        
Eutrophication occurs due to excessive use of these compounds, which can lead to having dead zones in bodies of water. 
Dead zones refers to areas with decreased levels of oxygen in the bodies of water caused by eutrophication and other factors. These affect the marine life negatively as fishes are also dependent on oxygen. 
Eutrophication is defined as the presence of excess minerals in the water, which causes dense growth of plants and leads to depletion of oxygen that make the animals in the water to die. 
        
                    
             
        
        
        
The Answer -
A. The amount of land available for lumber production decreases. 
Do to the Urban development there is fewer land and less trees to grow and cut down for lumber, which can lead in a decrees if production for lumber.
        
                    
             
        
        
        
Answer:
Hi, there your answer is D.Crossing Over
Hope This Helps
PLZ CORRECT ME IF I AM WRONG :)
Explanation: