Which answer would score higher? Not sure where to start? Explain this Answer A For the ohmic resistor, keeping temperature constant means resistance remains constant, so current is directly proportional to potential difference. In the lamp, increasing potential difference increases current and heats the filament. The higher filament temperature increases its resistance, so the lamp's resistance is not constant; temperature change, rather than current alone, explains the change. Answer B For the ohmic resistor, keeping temperature constant means resistance remains constant, so current is directly proportional to potential difference. In the lamp, increasing potential difference increases current through the filament. The larger current itself increases the lamp's resistance, so its resistance is not constant; it would rise even if the filament's temperature stayed constant.