As shown, two resistors are arranged in series with a $6.0\,\text{V}$ power supply. Determine the resistance of the variable resistor $R$ so that the potential difference across the $12\,\text{k}\Omega$ resistor is $1.0\,\text{V}$.
- A$2.0\,\text{k}\Omega$
- B$10\,\text{k}\Omega$
- C$60\,\text{k}\Omega$
- D$72\,\text{k}\Omega$