Which of the following can generate a difference of potential through chemical action?

The correct choice is a dry cell, as it generates a difference of potential through chemical action. A dry cell is a type of electrochemical cell that converts chemical energy into electrical energy. This process occurs due to the chemical reactions between the electrolyte and the electrodes within the cell. The resulting movement of ions creates an electric potential difference, allowing for the flow of current when the circuit is closed.

In contrast, a light bulb primarily functions by converting electrical energy into light through resistance, rather than generating potential itself. A generator converts mechanical energy into electrical energy, usually through electromagnetic induction rather than chemical action. A conductor, on the other hand, is a material that allows electric current to flow; it does not generate potential but rather facilitates the movement of electrons when a potential difference is applied. Therefore, the unique chemical process that occurs in a dry cell is what distinguishes it as the correct answer.