Assertion (A): The resistance of a copper specimen changes by about 22% when temperature is increased from room temperature to 700°C. Reason (R): The physical properties of a material are determined mostly by the extent of impurities.

• Both A and R are true and R is correct explanation of A
• Both A and R are true but R is not correct explanation of A
• A is true but R is false
• A is false but R is true