THE WALL STREET JOURNAL/DOW JONES NEWSWIRES: British Watchdog Will Examine Why Price of Natural Gas Rose: ??????will investigate contracts that involved companies such as Exxon Mobil Corp., Royal Dutch/Shell Group, BP PLC and Centrica PLC because it doesn???t rule out market manipulation.???: A Shell spokesman declined to comment on the detail of Ofgem???s analysis until the company has examined i