Seismic waves are waves of energy that travel through the Earth's layers, and are a result of earthquakes, volcanic eruptions
        
                    
             
        
        
        
-10grade/week
Explanation:
Given parameters: 
Initial grade = 95grade
Final grade = 65grade
Time = 3weeks
Unknown parameter: 
Rate of change of grade = ? 
Solution: 
Rate is defined as the change of a quantity with time. 
  Rate of change of grade  = 
Rate of change of grade  =  =
 = 
Rate of change of grade = -10grade/week
The rate of change of the student's grade is -10grade/week. It implies that the grade of the student reduces by 10unit per week. 
 
        
             
        
        
        
The correct answer is option C) A wet spring before vegetation is growing. A lack of roots holding soils and sediments together and an over-abundance of water can result in mass movements.
 
        
                    
             
        
        
        
"C" The only way something will make a shockwave or a sonic boom is if it's traveling faster than the speed of sound