This is a test of commonsense with single/multi-choices. Complete the next sentence:

How to create a potato battery
Gather the necessary materials.
To make a single potato battery you will need a potato, a galvanized nail, a copper coin, two alligator clip leads with clips on both ends, and a voltmeter.
Galvanized nails are standard nails that have a zinc coating.

Available choices: (I) They are a good fit for your battery since they do not rub between your hands. Galvanized nails attach directly to conductive metal that can withstand high temperatures.; (II) They can be purchased at any hardware or home improvement store. Use a fresh potato as the experiment depends upon the juices inside the potato.; (III) Galvanized nails are a standard procedure used to crimp copper pennies into sockets. Galvanized nails can be bought at hardware and electronics stores.; (IV) If you can't find galvanized nails online, you can purchase a nail kit at your local hardware store. Wire a rust resistant wire with fat-soluble dha.;
The answer is:
(II)