I think b but I’m not completely sure
An atom. Hope this helped
Explanation:
Charges,

The distance between charges, r = 10 cm = 0.1 m
We need to find the magnitude and direction of the electric force. It is given by :

So, the required force between charges is 36 N and it is towards positive charge i.e. +8 μC.
A wave looses its power as it comes to shore because it gets less deeper every second it gets closer to shore