What type of conduit is circular and made of metal?

The best choice for a type of conduit that is circular and made of metal is intermediate metal conduit (IMC). IMC is a rigid metallic conduit that is lightweight yet able to provide excellent protection against physical damage and corrosion. Its circular shape allows for effective routing of electrical wires and is commonly used in industrial, residential, and commercial applications.

Electrical metallic tubing (EMT) is another type of metal conduit that is also circular; however, it is thinner than IMC and primarily designed for areas where flexibility and lightweight construction are prioritized. This makes it more suitable for indoor applications where severe physical protection isn't as critical.

PVC conduit, on the other hand, is not metal at all; it is made from polyvinyl chloride and is primarily used in areas where corrosion resistance and moisture protection are needed, such as underground installations. Flexible conduit is typically not circular in the same rigid sense as IMC or EMT; it is designed to provide flexibility in installations where bends or movement might be necessary.

Therefore, selecting intermediate metal conduit is correct because it aligns with the characteristics of being circular and made of metal while fulfilling specific installation needs in various settings.