Each of the following statements concerning retroviruses is correct EXCEPT:

  •  During infection, the virus synthesizes a DNA copy of its RNA, and this DNA becomes covalently integrated into host cell DNA.
  •  The viral genome consists of three segments of double-stranded RNA.
  •  The virion is enveloped and enters cells via an interaction with specific receptors on the host cell.
  •  The virion carries an RNA-directed DNA polymerase encoded by the viral genome.