With rise in temperature the resistance of pure metals

Increases
Decreases
First increases and then decreases
Remains constant

The correct answer is A. Increases.

The resistance of a pure metal increases with rise in temperature. This is because the increase in temperature causes the atoms of the metal to vibrate more, which in turn increases the collisions between the electrons and the atoms. These collisions scatter the electrons, which makes it more difficult for them to flow through the metal, and hence the resistance increases.

Option B is incorrect because the resistance of a pure metal increases with rise in temperature. Option C is incorrect because the resistance of a pure metal does not first increase and then decrease with rise in temperature. Option D is incorrect because the resistance of a pure metal does not remain constant with rise in temperature.