Which objects will likely have the smallest gravitational force between them?

Explanation:

the objects having very small masses and greater distance between themyou will understand better using  the newtons law of gravitation

which states that

                     F=m₁m₂/r²

this clearly shows that smaller are the masses smaller would be the force of gravitation and vice versa

one "light year" is the distance that light travels, through vacuum, in one julian year.   that's 365.25 days, of 24 hours each.