A cosmic-ray proton in interstellar space has an energy of 18.0 MeV and executes a circular orbit having a radius equal to that of Jupiter's orbit around the Sun (7.78 ✕ 1011 m). What is the magnetic field (in T) in that region of space?

I'm thinking it's 2 you are asked to explain the earth's magnetic field. which is the best reply? 1. the earth's magnetic south is similar to the north pole of a magnet. 2. the earth's core has a strong magnetic charge similar to the south pole of a magnet. 3. the earth's geomagnetic south is similar to the south pole of a magnet. 4. the earth's magnetic charge is not centered at either pole; it varies based on location.