Which one of the following statements with regard  to  Jet  stream,  an  upper  level tropospheric wave, is not correct?

• A. It is narrow band of high-velocity wind.
• B. It   follows   the   wave   path   near   the tropopause at elevations of 8 km to 15 km.
• C. Jet  streams  are typically  continuous over long distances.
• D. In summer, the polar front jet achieves its maximum force.