Correct Answer - D
`mu_(r)=1+I/H`, as we know I dependent on `H`, initially value of `I/H` is smaller so value of `mu_(r)` increases with `H` but slowly but with further increases of `H` value of `I/H` also increases i.e., `mu_(r)` increases speedily. When material fully magnetised `I` becomes constant then with the increase of `H(I/H decreases) mu_(r)` decreases. This is confirm with the option (d).