Which body organ is surrounded by by a series of tubes that are used for the transport of oxygen. what do we normally call these transport tubes

Hemoglobin: The protein inside red blood cells (a) that carries oxygen to cells and carbon dioxide to the lungs is hemoglobin (b). Hemoglobin is made up of four symmetrical subunits and four heme groups. Iron associated with the heme binds oxygen. It is the iron in hemoglobin that gives blood its red color.

answer:

advil

explanation:

having the certification could make the person more required to do a certain thing then another.this could also lead to different job offers or opportunities.