Which describes the requirements for making an electromagnet?

a.
a battery, a length of wire, and an iron nail must be connected in an open series circuit. in addition, the wire must be coiled around the body of the battery.

b.
a battery, a length of wire, and an iron nail must be connected in an open parallel circuit. in addition, the wire must be coiled around the body of the battery.

c.
a battery, a length of wire, and an iron nail must be connected in a closed series circuit. in addition, the wire must be coiled around the body of the nail.

d.
a battery, a length of wire, and an iron nail must be connected in a closed parallel circuit. in addition, the wire must be coiled around the body of the nail.