Assertion : The temperature coefficient of resistance is positive for metals and negative for P-type semiconductor. Reason : The effective charge carriers in metals are negatively charged whereas in P-type semiconductor they are positively charged. [AIIMS 1996]

• A. If both assertion and reason are true and the reason is the correct explanation of the assertion.
• B. If both assertion and reason are true but reason is not the correct explanation of the assertion.
• C. If assertion is true but reason is false.
• D. If the assertion and reason both are false.
• E. If assertion is false but reason is true.