In a step-down transformer, the AC output current is less than the input current. This is because a step-down transformer is designed to decrease the voltage from the input to the output. According to Ohm`s Law, current is directly proportional to voltage. Therefore, when the voltage decreases, the current also decreases.

Option 1 states that the AC output current is more than the input current, which is incorrect. The output current is always less than the input current in a step-down transformer.

Option 2 correctly states that the AC output current is less than the input current, which is the correct answer.

Option 3 suggests that the current remains the same in the step-down transformer, which is incorrect. The current decreases along with the voltage.

Option 4 states that the output voltage is more than the input voltage, which is not directly related to the question being asked. The step-down transformer decreases the voltage, not increases it.

Therefore, the correct answer is option 2, as it accurately describes the behavior of a step-down transformer.