Question

to examine circuits that produce magnetic fields, which relationship (between the following pairs) could we test?
compass angle and resistance
wire loops and resistance
wire type and current
resistance and voltage

Explanation:

A compass detects magnetic fields; the angle of a compass needle shifts with the strength of the magnetic field produced by a circuit. Circuit resistance affects current, which in turn affects the magnetic field strength (and thus the compass angle). The other pairs either relate to electrical properties not directly tied to magnetic field production (resistance/voltage, wire type/current, wire loops/resistance) without linking to a measurable magnetic field indicator.

Answer:

compass angle and resistance