The correct answer is option 3: 1 and 2 only. A transformer is a device that is primarily used to convert high AC voltage to low voltage or low AC voltage to high voltage. It is not designed to convert direct current to alternating current (option 3) or regulate the fluctuation of voltage (option 4).

Option 1 states that a transformer is used to convert low AC voltage to high voltage, which is incorrect. Transformers are specifically designed to step-up or step-down voltage, depending on the needs of the application. A step-up transformer increases the voltage, while a step-down transformer decreases the voltage.

Option 2 states that a transformer is used to convert high AC voltage to low voltage, which is correct. This is the main function of a transformer. It is commonly used in power distribution systems to step-down the high voltage from power stations to a lower, more manageable voltage for delivery to households and businesses.

Option 3 incorrectly suggests that a transformer can convert direct current to alternating current, which it cannot do. Only specific devices such as inverters or converters are able to perform this function.

Option 4 incorrectly states that a transformer is used to regulate the fluctuation of voltage. Transformers are passive devices and do not have