Q6. A conductor has a resistivity of \( 7 \times 10^{-8} \, \Omega \text{m} \) and \( \alpha = 4 \times 10^{-3} \, ^\circ\text{C}^{-1} \) at \( 25^\circ \text{C} \). What is its resistivity at \( 85^\circ \text{C} \)?
- A. \( 8.2 \times 10^{-8} \, \Omega \text{m} \)
- B. \( 8.5 \times 10^{-8} \, \Omega \text{m} \)
- C. \( 8.68 \times 10^{-8} \, \Omega \text{m} \)
- D. \( 9.0 \times 10^{-8} \, \Omega \text{m} \)