The temperature dependence of resistances of $Cu$ and undoped $Si$ in the temperature range $300-400 \ K$ is best described by:

• A
  Linear increase for $Cu$,exponential decrease for $Si$
• B
  Linear decrease for $Cu$,linear decrease for $Si$
• C
  Linear increase for $Cu$,linear increase for $Si$
• D
  Linear increase for $Cu$,exponential increase for $Si$