The expression if given as,
![(1-k)/(1-n)](https://img.qammunity.org/2023/formulas/mathematics/college/k5g1iqbkqelnjgtc1s9jqbvz4kw8fgyhds.png)
The condition is given as,
![n=(1)/(k)](https://img.qammunity.org/2023/formulas/mathematics/college/61ylsg8iv7t42ucavlrnmc36chwriqvorv.png)
Substitute this value in the expression,
![=(1-k)/(1-(1)/(k))](https://img.qammunity.org/2023/formulas/mathematics/college/w40wrh9oeowu25m16phcm41wlk0i2ey184.png)
Resolve the rational expression as,
![\begin{gathered} =(1-k)/(((k-1)/(k))) \\ =(k(1-k))/(k-1) \\ =(-k(k-1))/(k-1) \end{gathered}](https://img.qammunity.org/2023/formulas/mathematics/college/96z5496ckv7khvpe869mdu5s03miko6z4v.png)
Cancelling out the common factor,
![\begin{gathered} =(-k(1))/((1)) \\ =-k \end{gathered}](https://img.qammunity.org/2023/formulas/mathematics/college/oki6xakfmsnyr50hlal16hzn5aopjq292b.png)
Thus, the simplified form of the given expression is obtained as,
![-k](https://img.qammunity.org/2023/formulas/mathematics/college/9xmvszzthr5x6grzg90pberxcqqv9ud6o0.png)
Therefore, option B is the correct choice.