The answer is D) Humerus. Hope this helps :)
 
        
                    
             
        
        
        
Answer
Ocean acidification results from the solubility of CO2 in oceans increasing the H+ concentrations, and depletion of bicarbonates concentrations.
Therefore, human activities which increases the concentration of CO2 in the atmosphere, will raise the atmospheric  CO2 concentration. CO2 is constantly being absorbed by green plants maintaining   its concentration through carbon cycle,Therefore massive deforestation  which removes green plants, cutting  down photosynthesis is one of human activities which  raises CO2 levels of the atmosphere.The CO2 dissolves in  the oceans to raise its acidic levels.Lower pH.
Another source is fossil fuels emissions which add more CO2 to the atmosphere. 
Explanation:
 
        
             
        
        
        
mechanical weathering
Mechanical weathering is the process of breaking big rocks into little ones. This process usually happens near the surface of the planet. Temperature also affects the land. The cool nights and hot days always cause things to expand and contract. That movement can cause rocks to crack and break apart.Mechanical weathering involves mechanical processes that break up a rock: for example, ice freezing and expanding in cracks in the rock.