* Gravity and Mass: The strength of gravitational force depends on the mass of the objects involved. The more massive an object, the stronger its gravitational pull.

* Distance: Gravity also weakens with distance. The farther away you are from an object, the weaker its gravitational pull.

Let's compare:

* Earth: You are standing on the Earth's surface, making it the closest and most massive object influencing you.

* Sun: While the Sun is much more massive than the Earth, it's also incredibly far away. Its gravitational pull is still significant, responsible for keeping Earth in orbit, but it's much weaker than the Earth's pull on you.

* Moon: The Moon is much less massive than the Earth and also farther away. It exerts a weaker gravitational pull on you.

* Book: A book has negligible mass compared to the Earth, Sun, or Moon. Its gravitational pull on you is practically nonexistent.

Therefore, the Earth exerts the strongest gravitational force on you.