In the given question, we need to identify the true representation of (i) variable DC potential, (ii) rheostat, and (iii) AC ammeter from the given options.

Option 1: The question does not provide any visual representation for option 1, so we cannot determine if it represents the required components or not.

Option 2: Similarly, the question does not provide any visual representation for option 2, so we cannot determine if it represents the required components or not.

Option 3: This is the correct answer. The visual representation in option 3 shows a variable DC potential, which typically consists of a power supply connected to a variable resistor. The rheostat is represented as a variable resistor. Lastly, the AC ammeter is represented by a symbol with a round base and a straight line on top.

Option 4: The question does not provide any visual representation for option 4, so we cannot determine if it represents the required components or not.

To summarize, option 3 is the true representation of (i) variable DC potential, (ii) rheostat, and (iii) AC ammeter.