Please answer the following question: Information:  - SeaWorld is a United States chain of marine mammal parks, oceanariums, animal theme parks, and rehabilitation centers owned by SeaWorld Entertainment (one park will be owned and operated by Miral under a license). The parks feature killer whale, sea lion, and dolphin shows and zoological displays featuring various other marine animals. There are operations located within the United States in Orlando, Florida; San Diego, California; San Antonio, Texas; later outside the United States such as Abu Dhabi, United Arab Emirates; and previously Aurora, Ohio. On March 5, 2007, SeaWorld Orlando announced addition of the Aquatica water park to its adventure park family, which already includes SeaWorld and Discovery Cove.  - The term rolling stock originally referred to any vehicles that move on a railway. It has since expanded to include the wheeled vehicles used by businesses on roadways. It usually includes both powered and unpowered vehicles, for example locomotives, railroad cars, coaches, and wagons.  - Big Bad Wolf was a suspended roller coaster in the Oktoberfest section of Busch Gardens Williamsburg . First opened on June 15 , 1984 , the ride operated for 25 years , and was closed on September 7 , 2009 . The footers , queue line , and station were left standing and have been re-purposed for Verbolten , an attraction introduced in the 2012 season . The complete # 2 train , some sections of track , the ride control panel , and other artifacts from the ride such as lift chain segments and chain dogs were sent to the National Rollercoaster Museum .  - Busch Gardens Williamsburg (formerly known as Busch Gardens Europe and Busch Gardens: The Old Country) is a theme park located in James City County, Virginia, about 60.40 miles (97.20 km) northwest of Virginia Beach, originally developed by Anheuser-Busch (A-B) and currently owned by SeaWorld Entertainment, a division of Blackstone Group. The park opened on May 16, 1975, adjacent to Anheuser-Busch's brewery and near its other developments including the Kingsmill Resort complex. The park is themed around various European countries.  - A steel roller coaster is a roller coaster that is defined by having a track made of steel. Steel coasters have earned immense popularity in the past 50 years throughout the world. Incorporating tubular steel track and polyurethane-coated wheels, the steel roller coasters can provide a taller, smoother, and faster ride with more inversions than a traditional wooden roller coaster.  - A suspended roller coaster is a type of steel roller coaster in which the car hangs from the bottom of the rolling stock by a pivoting fulcrum or hinge assembly. This allows the car and riders to swing side to side as the train races along the track. Due to the swing designs, these roller coasters cannot invert riders.    After reading the paragraphs above, we are interested in knowing the entity with which 'big bad wolf ' exhibits the relationship of 'subclass of'. Find the answer from the choices below.  Choices: - animal  - arab  - beach  - chain  - city  - country  - county  - division  - entertainment  - family  - march  - marine mammal  - park  - roller  - rolling stock  - sea  - steel  - steel roller coaster  - suspended roller coaster  - term  - type  - water park  - whale  - wooden roller coaster  - world
A:
steel roller coaster