The collector contact region is doped with higher concentration of n-type impurities due to . . . . . . . . A. It creates a depletion region at the contact surface B. It creates a low conductivity path between collector region and contact C. It reduces contact resistance D. It can withstand high voltages as compared to collector region

The correct answer is: C. It reduces contact resistance.

The collector contact region is doped with higher concentration of n-type impurities to reduce contact resistance. This is because the higher concentration of n-type impurities creates a larger number of free electrons in the collector region. These free electrons can then flow more easily through the contact region, reducing the resistance of the contact.

Option A is incorrect because the depletion region is created by the difference in doping concentration between the collector region and the base region. The higher concentration of n-type impurities in the collector region creates a depletion region at the contact surface, but this is not the reason why the collector contact region is doped with higher concentration of n-type impurities.

Option B is incorrect because the low conductivity path between the collector region and the contact is created by the depletion region. The depletion region is a region of high resistance, but this is not the reason why the collector contact region is doped with higher concentration of n-type impurities.

Option D is incorrect because the collector region can withstand high voltages as compared to the base region, but this is not the reason why the collector contact region is doped with higher concentration of n-type impurities.