Question: The Railpower GG20B "Green Goat" is powered by an item sold by what American corporation?

Context paragraphs:
Syntax-Brillian Corporation: Syntax-Brillian Corporation was an American corporation formed on November 30, 2005, by the merger of Syntax (seller of widescreen HDTV-ready LCD televisions) with Brillian Corporation (seller of Brillian brand televisions).  The company sold HDTVs under the brand name of Ölevia and its stock was previously listed on the Nasdaq Stock Market under the ticker symbol BRLC.  It was based in Tempe, Arizona.  In 2009, it resolved a bankruptcy proceeding by selling all its assets to Emerson Radio Corp.

Selina Trieff: Selina Trieff (born in Brooklyn, 1934 - 14 January 2015) was an American artist who painted and exhibited for over fifty years.  Trieff painted archetypal figures in a flattened and heavily delineated manner, which acted at once as self-portraits and allegories for the human condition.  She developed her singular style of figuration through her strong abstract roots which continued to evolve throughout her life.  Although she most often painted figures and animals, Trieff considered herself an abstract artist.  Among her animal paintings are "Green Goat with Moon" (1983), "Two Figures with Goat" (1997), "Three Figures with Green Goat" (1992) and "Connected" (1996).

Laura Chenel: Laura Chenel is a cheese maker who was America's first commercial producer of goat cheese, and helped to popularize goat cheese in America.  In 1979, she began producing chèvre in the Bay Area town of Sebastopol, California, after a fact-finding trip to visit goat cheese producers in France.  After several months of working to sell her product to local markets (with mixed success, due to American unfamiliarity with goat cheeses at the time), she received her first major opportunity when Alice Waters of Chez Panisse in Berkeley, California placed a standing order for her cheese in 1980.  Waters listed the cheese by name on her menu (as "Laura Chenel's Chèvre", in what may have been the first American instance of goat cheese salad), which provided Chenel with a great deal of publicity.  Eventually, her operation would grow to sell over two million pounds of cheese per year.  The company primarily manufactures fresh chèvre, although aged cheeses make up roughly 10% of its business.  In 2006, Chenel sold the company to the Rians Group, a French corporation which has purchased multiple small farming operations, while retaining ownership of her herd of five hundred goats.

Railpower GG20B: The Railpower GG20B "Green Goat" is a low-emissions diesel hybrid switcher locomotive built by Railpower Technologies Corp. It is powered by a single Caterpillar C9 six cylinder inline engine developing 300 hp , which is also connected to a large battery bank where both sources combine for a total power output of 2000 hp .  To date, there have been more than 50 GG20B diesel hybrid genset switchers manufactured since their first introduction in 2004.

CQout: CQout (pronounced 'Seek You Out') is a UK based online auction company.  CQout was launched in 1999 by three London Business School Graduates; Tony Newton, Siamak Bashi, and Mike Rees.  By number of items listed, CQout is the UK's 2nd largest online auction website.  A proportion of the final selling price for each item sold via the CQout website is taken as an alternative to charging listing fees.

Boston Garden-Arena Corporation: The Boston Garden-Arena Corporation was an American corporation that oversaw the operations of the Boston Garden from 1934 to 1973.  It was formed when the Boston Arena Corporation gained control of the Boston Garden from the Madison Square Garden Corporation in 1934.  From 1946 to 1950 it owned the Boston Celtics.  In 1951 it purchased controlling interest in the Boston Bruins from Weston Adams.  In 1953 it sold the Boston Arena to Samuel M. Pinsly for $398,000.  In 1973, the Boston Garden-Arena Corporation merged with Storer Broadcasting.

American Dairy Goat Association: The American Dairy Goat Association or ADGA is a United States not-for-profit corporation dedicated to dairy goats.  Its purpose is to promote the dairy goat industry, by providing and circulating sound information about goats and goats' milk; maintaining and publishing herd books and production records of milk goats; and issuing certificates of registration and recordation; improving and developing the milk goat breeds; and providing publicity and service for the goat dairying industry.  The principal operation of the corporation is in Columbia, Missouri, and its headquarters are in Spindale, North Carolina.

Railpower Technologies: Railpower Technologies Corp. is a subsidiary of R.J. Corman Railroad Group that builds environmentally friendly hybrid Green Goat and Genset switching locomotives, founded by Frank Donnelly and Gerard Koldyk.  Its locomotives have been purchased by Canadian Pacific Railway, BNSF Railway, Kansas City Southern Railway and Union Pacific Railroad among others.

Marginal revenue: In microeconomics, marginal revenue (R') is the additional revenue that will be generated by increasing product sales by one unit.  It can also be described as the unit revenue the last item sold has generated for the firm.  In a perfectly competitive market, the additional revenue generated by selling an additional unit of a good is equal to the price the firm is able to charge the buyer of the good.  This is because a firm in a competitive market will always get the same price for every unit it sells regardless of the number of units the firm sells since the firm's sales can never impact the industry's price.  However, a monopoly determines the entire industry's sales.  As a result, it will have to lower the price of all units sold to increase sales by 1 unit.  Therefore, the marginal revenue generated is always lower than the price the firm is able to charge for the unit sold, since each reduction in price causes unit revenue to decline on every good the firm sells.  The marginal revenue (the increase in total revenue) is the price the firm gets on the additional unit sold, less the revenue lost by reducing the price on all other units that were sold prior to the decrease in price.

Caterpillar Inc.: Caterpillar Inc. () is an American corporation which designs, develops, engineers, manufactures, markets and sells machinery, engines, financial products and insurance to customers via a worldwide dealer network.

Supporting paragraphs: Railpower GG20B Caterpillar Inc.
Answer: Caterpillar Inc.