Final answer:
Magnetic fields can be shielded with certain materials, but gravitational fields cannot be shielded.
Step-by-step explanation:
Magnetic fields can be shielded through the use of certain materials that are capable of redirecting or absorbing magnetic field lines. This is achieved by creating a closed loop of highly permeable material, such as iron or steel, which creates an alternate path for the magnetic field lines to follow, preventing them from penetrating beyond the shield.
Gravitational fields, on the other hand, cannot be shielded in the same way as electric or magnetic fields. Gravitational fields are a fundamental property of mass and cannot be blocked or manipulated using materials or barriers. Therefore, the correct answer is option d) No, magnetic fields can be shielded, but gravitational fields cannot.