The correct answer is D. infinite.
A transformer is an electrical device that transfers energy from one circuit to another through electromagnetic induction. The primary winding of the transformer is connected to the input circuit, and the secondary winding is connected to the output circuit. The voltage and current in the secondary winding are related to the voltage and current in the primary winding by the transformer ratio, which is the number of turns in the secondary winding divided by the number of turns in the primary winding.
The resistance between the primary and secondary windings of a transformer is infinite because there is no physical connection between the two windings. The only connection between the two windings is the magnetic field that is created by the current flowing through the primary winding. The magnetic field induces a voltage in the secondary winding, but there is no direct current flow between the two windings.
Option A is incorrect because the resistance between the primary and secondary windings of a transformer is not zero. Option B is incorrect because the resistance between the primary and secondary windings of a transformer is not 1 ohm. Option C is incorrect because the resistance between the primary and secondary windings of a transformer is not 1000 ohms.