The key to answering this question is the Hysteresis Curve (below) which shows how the applied magnetizing force H is related to the magnetization M produced, as measured by flux density B in the sample.
The significant features of the curve are :
(1) saturation - the magnetization cannot increase above the limit at which its magnetic domains are completely aligned with the external field), and
(2) retentivity or remanence - when the applied field is switched off the material remains magnetized.
Assuming the sample is initially unmagnetised (t=0), the magnetization M increases with H, initially in proportion to it but gradually becoming saturated (O to a). As H is reduced to zero (t=4) some magnetization M remains (a to b). As H is increased in the reverse direction there is a steep fall in M until it becomes saturated again at the other extreme (b to c to d). Finally as H is reduced to zero (t=8) M decreases but the material retains some magnetism in the reverse direction (d to e).
These changes correspond to graph # 2.
Although graph # 1 shows saturation it shows no retentivity / remanence - ie when H returns to 0 then M also returns to zero. This is typical of paramagnetic materials. In contrast, iron is ferromagnetic and retains some of its induced magnetism.
Graph # 3 also shows some saturation and no retentivity. However in this case the magnetization is in the opposite direction to the applied field. Such materials are diamagnetic.
Graph # 4 is not typical of any type of magnetic material.
