Which of the following pairs of objects would have the strongest gravitational pull?

two buildings in the same city ←
two tall buildings in different cities
two stars very far away from each other
two stars very close to each other

my answer is c

I would say d.

To determine which pair of objects would have the strongest gravitational pull, we need to consider the mass and distance between the objects.

The strength of gravity depends on the mass of the objects. The greater the mass, the stronger the gravitational pull.

In this case, the pair of objects with the greatest mass would be the two stars very close to each other. Stars are enormous celestial bodies with immense mass, much greater than buildings. Therefore, they would have a stronger gravitational pull compared to buildings.

It is worth noting that for objects that are far apart, the strength of gravity decreases rapidly as the distance increases. So, even though the two stars are far away from each other (option c), if they are relatively close compared to the distance between the buildings in the same city (option a) or the buildings in different cities (option b), the gravitational pull between the stars would still be stronger.

Hence, your answer that option c, two stars very close to each other, would have the strongest gravitational pull, is correct.