The correct answer is:

Both A and R are true, and R is the correct explanation of A.

Explanation:

Assertion (A) states that the temperature of a metal wire rises when an electric current is passed through it, which is true. When an electric current flows through a metal wire, the wire experiences resistance, and this resistance leads to the generation of heat. This phenomenon is known as Joule heating or the Joule effect. The electric current causes the free electrons in the metal wire to collide with the metal atoms, and these collisions result in the conversion of electrical energy into heat energy. As a result, the temperature of the wire increases.

Reason (R) states that the collision of metal atoms with each other releases heat energy, which is also true. In any solid material, including metals, the atoms or ions are in constant motion. When the metal atoms collide with each other, kinetic energy is transferred, and this energy can manifest as heat. In the context of an electric current passing through a metal wire, the collisions between free electrons and metal atoms contribute to the release of heat energy.

Therefore, both the assertion (A) and the reason (R) are true, and the reason (R) correctly explains why the temperature of a metal wire rises when an electric current is passed through it.