The correct answer is B. lead.
The Edison cell is a primary cell that was invented by Thomas Edison in 1899. It is a wet cell, meaning that it contains a liquid electrolyte. The negative plate of an Edison cell is made of lead, while the positive plate is made of iron. The electrolyte is a solution of sulfuric acid.
When the cell is in use, the lead on the negative plate is oxidized, while the iron on the positive plate is reduced. This reaction produces an electric current. The Edison cell is a relatively inefficient cell, but it is also a very durable cell. It can be used in a variety of applications, including flashlights, lanterns, and emergency power supplies.
The other options are incorrect for the following reasons:
- Copper is not a suitable material for the negative plate of an Edison cell. Copper is not as reactive as lead, so it would not produce as much electricity.
- Iron is the material used for the positive plate of an Edison cell. The negative plate must be a different material in order to produce a current.
- Silver oxide is not a suitable material for the negative plate of an Edison cell. Silver oxide is a very reactive material, so it would quickly be consumed by the reaction.