Answer:
1. Hydrogen
Explanation:
The interior of these planets contains liquid hydrogen (the Earth has liquid iron in it).
When this element is subjected to tremendous pressures (as in Jupiter and Saturn), the electrons of each hydrogen atom can "jump" to other atoms. This property allows liquid hydrogen to behave with a metal.
With the rotation of the planets and the large amount of constant energy emitted by the nucleus, currents are induced in liquid hydrogen, giving rise to magnetic fields that propagate for millions of kilometers in space (Jupiter's magnetic field is fourteen times stronger than Earth's, for example).
