Step 1: Look at what is moving.
A satellite goes around the Earth in an oval (elliptical) orbit, so we need the law that describes orbital motion around a central body.
Step 2: Check Newton's laws.
Newton's laws explain forces in general, but they do not by themselves describe the shape and timing of an orbit.
Step 3: Check Kepler's laws.
Kepler's three laws were made exactly for bodies orbiting a central mass: orbits are ellipses, equal areas are swept in equal times, and the square of the period relates to the cube of the orbit size.
Step 4: Rule out the others.
Relativity is only needed for very strong gravity, and Kirchhoff's laws are about electric circuits, not orbits.
Step 5: Match the satellite case.
A satellite's elliptical path and orbital period fit Kepler's laws directly.
Step 6: Conclude.
The most applicable law is Kepler's law.
\[ \boxed{\text{Kepler's laws}} \]