If a burden voltage is allowed, either just use a resistor to convert current to voltage and use a summing amplifier with an offset voltage.
Since this is an exam question, I think the concept is purely theoretical and a burden voltage is not allowed.
I guess you have been taught all the basic nullor circuits. Just use the concept for a transimpedance amplifier, either with an offset current at the input, or compensated for the offset at the output.
Edit, if you are really looking for the bare minimum, (which is not the intention, I think) a single voltage supply with a single resistor is sufficient