Most locations in North America permit rigid metal or plastic (PVC) conduit (aka tubing or trunking).
Also permitted are flexible metal or plastic (PVC) conduit.
As is Romex® and other non-metallic sheath cables.
Note that the NEC code book only applies when a location (city or state) passes a law about it. That location may chose what year code book (2005, 2008, 2011 or 2014) to use. That location may also have exceptions and additions to the code book. Chicago & New York cities are examples of locations with lots of additional rules.
Also permitted are flexible metal or plastic (PVC) conduit.
As is Romex® and other non-metallic sheath cables.
Note that the NEC code book only applies when a location (city or state) passes a law about it. That location may chose what year code book (2005, 2008, 2011 or 2014) to use. That location may also have exceptions and additions to the code book. Chicago & New York cities are examples of locations with lots of additional rules.