The book of Revelation uses symbolic language extensively. What is the primary theological significance of the 'New Jerusalem' descending from heaven (Revelation 21:2)?

A It represents the physical rebuilding of Jerusalem after a future war. B It symbolizes the complete and final union of God with humanity, a restored creation where heaven and earth are perfectly joined. C It refers to a literal city floating in the sky, accessible only to believers. D It signifies the establishment of a new political kingdom ruled by the saints.