Question Analysis: Assertion (A) and Reason (R) type question.

Step 1 (Analysis of Assertion):

• For metals, resistance $R$ increases with temperature $T$ due to increased collision frequency of electrons with lattice ions. Thus, the temperature coefficient of resistance ($\alpha$) is positive.
• For semiconductors (including p-type), resistance $R$ decreases with temperature $T$ because the number density of charge carriers increases exponentially. Thus, $\alpha$ is negative.
• Assertion (A) is True.

Step 2 (Analysis of Reason):

• In metals, charge carriers are indeed electrons (negatively charged).
• In p-type semiconductors, the majority charge carriers are holes, which behave as positively charged entities.
• Reason (R) is True.

Step 3 (Logical Correlation):

• The sign of the temperature coefficient of resistance depends on the mechanism of conduction (scattering vs. carrier generation), not merely the sign of the charge of the carriers.
• The negative temperature coefficient in semiconductors is due to the increase in the number of charge carriers ($n$) with temperature, which outweighs the decrease in relaxation time ($\tau$). The formula for resistivity is $\rho = \frac{m}{ne^2\tau}$.
• Therefore, Reason (R) is a true statement, but it is not the correct explanation for Assertion (A).

Final Answer:

Option: (b) Both Assertion (A) and Reason (R) are true but Reason (R) is not the correct explanation of Assertion (A).