Answer: Saturn
Explanation:
Magnetic field of a planet exists because of metal present in molten form in the core. The motion of this molten metal creates a magnetic field.
Core of Earth contains Iron and nickel present in molten state. Thus, a huge magnetic field surrounds the Earth.
Mars and Venus do not have magnetic field.
The magnetic field of Neptune is exists due electrically -conducting water present in it.
Saturn is a giant gaseous planet which is composed of hydrogen nd helium. The magnetic field of the Saturn is present due to liquid hydrogen in its core.