the presence of a fluid mantle the presence of Van Allen belts the presence of gravitational force the presence of water in three states
Earth's core consists primarily of iron. Which observation about another planet would provide some evidence that the planet has an iron core?

Options:
- the presence of a fluid mantle
- the presence of Van Allen belts
- the presence of gravitational force
- the presence of water in three states

the presence of Van Allen belts