A

Step 1: Understand the intrinsic behavior of semiconductors. Semiconductors are materials with a conductivity between that of insulators and conductors. The number of charge carriers in semiconductors is significant for their conductivity.
Step 2: Analyze how temperature affects semiconductors. When a semiconductor is heated, thermal energy is provided to the electrons in the material, which helps them overcome the energy band gap and move from the valence band to the conduction band.
Step 3: As more electrons are excited into the conduction band, the number of charge carriers increases, leading to a higher conductivity and, consequently, a decrease in resistance.
Step 4: Conclude that as the temperature increases, the resistance of the semiconductor decreases due to the increase in charge carriers.

Therefore, the correct answer is A.