The answer is D I took the test
I believe the answer is b) slowly heating the surface
Mass is a body of matter of indefinite shape and considerable size. Density is the degree to which something is filled. Check this website for more a better understanding : <span>www.answers.com/Q/What_is_the_relationship_between_density_and_volume</span>
Here we can use coulomb's law to find the force between two charges
As per coulombs law
]tex]F = \frac{kq_1q_2}{r^2}[/tex]
here we have




now by using the above equation we have


so here the force between two charges is of above magnitude and this will be repulsive force between them as both charges are of same sign.
your answer is.....
D. have a large atomic radius
although they also increase going from left to right so if D is incorrect, B might be your answer. it depends on context of the lesson.