How to distinguish between a pure resistance R and circuit whose equivalent reactance is R (when in a black box)?
Connect a resistor between A and the output of a signal generator; other lead of signal generator to B.  Connect channel 1 of your scope to the signal generator output and channel 2 of the scope to A. Sync the scope to channel 1.  Vary the frequency and observe phase shift, and amplitude of A with respect to channel 1.  If this doesn't make sense, I suggest you go read about LC resonance  and Q.  We can provide further assistance after you report your findings!