I think that’s the correct answer
 
        
        
        
Answer:
1.Stronger bones 2.Joint flexibility 
 
        
             
        
        
        
Answer with Explanation:
The force of attraction between 2 charges of magnitude separated by a distance 'r' is given by
 separated by a distance 'r' is given by
 
 
where
 is a constant known as permitivity of free space
 is a constant known as permitivity of free space

Applying the given values in the above relation we get

 
        
             
        
        
        
Answer:
In D: 3J
Explanation:
Potential energy: Ep=mgh where m is the mass, h altitude.
In point A: h=20cm=0.2m
Epa=12=0.2×mg. Thus mg=12/0.2=60N
For point D: hd=5cm=0.05m
Epd=mg×0.05=60×0.05=3J