Concept:Ohm’s law is obeyed by materials in which current is directly proportional to voltage, i.e. ohmic conductors.Explanation:Metals are ohmic conductors when temperature is constant, so they obey Ohm’s law: V=IR.Diodes and glass are non-ohmic or non-conductors.Electrolytes are not generally classified as obeying Ohm’s law in simple form.Answer:A. all metals