In the context of the input sentence, determine the relationship between 'Williams Companies' and 'natural gas'.
Options: original broadcaster, product/material produced, chairperson, manufacturer

Within this article: Details on U.S. natural gas pipeline projects, including those from major companies such as Kinder Morgan Incorporated ( KMI ), TransCanada Corporation ( TRP ), Spectra Energy Corporation ( SE ) and Williams Companies ( WMB ).
product/material produced