Ferromagnetic Material:
- In a ferromagnetic material, the magnetic moments of the atoms align parallel to each other in a specific direction.
- When an external magnetic field is applied, the magnetic moments align themselves with the external field, resulting in an increase in the overall magnetization of the material.
- This increase continues until the magnetic moments are fully aligned with the external field, reaching the saturation magnetization.
- As the external field is gradually removed, the magnetic moments start to randomize and lose their alignment, causing a decrease in magnetization.

Antiferromagnetic Material:
- In an antiferromagnetic material, adjacent atomic magnetic moments align in opposite directions, resulting in a cancellation of their overall magnetic effects.
- When an external magnetic field is applied, the alignment of the atomic magnetic moments changes, and the material becomes weakly magnetized.
- This magnetization increases as the field is further increased until a critical value is reached.
- Beyond this critical value, the alignment of the atomic moments becomes more complex, and the magnetization starts to decrease.

Paramagnetic Material:
- In a paramagnetic material, the magnetic moments of the atoms are randomly oriented.
- When an external magnetic field is applied, the magnetic moments tend to align with the field, causing an increase in magnetization.
- However, this alignment is not as strong as in ferromagnetic materials, and the increase in magnetization is relatively small.
- As the external field is removed, the magnetic moments return to their random orientations, causing a decrease in magnetization.

Diamagnetic Material:
- In a diamagnetic material, all the atomic magnetic moments are paired and cancel each other out, resulting in zero net magnetization.
- When an external magnetic field is applied, the atomic magnetic moments align themselves in opposition to the field, causing a weak magnetization.
- This magnetization is relatively small and opposes the applied field.
- As the external field is removed, the atomic moments return to their original orientations, and the magnetization decreases.

Conclusion:
Among the given options, the magnetization of an antiferromagnetic material increases and then decreases as the external magnetic field is increased and then decreased.