The relation $H \propto I$ and the susceptibility $\chi = \frac{I}{H}$ are not applicable for which of the following substances?

$A$ uniform magnetic field,parallel to the plane of the paper,exists in space and is initially directed from left to right. When a bar of soft iron is placed in the field parallel to it,the lines of force passing through it will be represented by:

On applying an external magnetic field to a ferromagnetic substance,the domains:

There are four light-weight rod samples $A, B, C, D$ separately suspended by threads. $A$ bar magnet is slowly brought near each sample and the following observations are noted:
$(i)$ $A$ is feebly repelled
$(ii)$ $B$ is feebly attracted
$(iii)$ $C$ is strongly attracted
$(iv)$ $D$ remains unaffected
Which one of the following is true?

Diamagnetic substances are

Consider the following two statements $A$ and $B$ and identify the correct choice in the given answers.
$A$. Paramagnetism is explained by domain theory.
$B$. Susceptibility of a diamagnetic substance is independent of temperature.