Question: What is the theme song of the attraction that was created by both Walt Disney and WED Enterprises as the prime feature of the General Electric (GE) Pavilion for the 1964 New York World's Fair?

Context paragraphs:
Walt Disney Imagineering: Walt Disney Imagineering Research & Development, Inc. is the research and development arm of The Walt Disney Company, responsible for the creation, design, and construction of Disney theme parks and attractions worldwide.  Founded by Walt Disney to oversee the production of Disneyland, it was originally known as Walt Disney, Inc. then WED Enterprises, from the initials meaning "Walter Elias Disney", the company co-founder's full name.

Magic Kingdom: Magic Kingdom is a theme park at the Walt Disney World Resort in Bay Lake, Florida, near Orlando.  Owned and operated by The Walt Disney Company through its Parks and Resorts division, the park opened on October 1, 1971, as the first of four theme parks at the resort.  Initialized by Walt Disney and designed by WED Enterprises, its layout and attractions are based on Disneyland Park in Anaheim, California, and is dedicated to fairy tales and Disney characters.

There's a Great Big Beautiful Tomorrow: "There's a Great Big Beautiful Tomorrow" is the theme song to two Disney attractions, Walt Disney's Carousel of Progress at the Magic Kingdom of Walt Disney World (formerly at Disneyland) and Innoventions at Disneyland.  It was also used in one scene of the Epcot attraction Horizons.

Westinghouse Time Capsules: The Westinghouse Time Capsules are two time capsules prepared by the Westinghouse Electric & Manufacturing Company: "Time Capsule I" was created for the 1939 New York World's Fair and "Time Capsule II" was created for the 1964 New York World's Fair.  Both are buried 50 feet below Flushing Meadows–Corona Park, the site of both world's fairs; the 1965 capsule was placed ten feet north of the 1939 capsule.  The capsules are to be opened at the same time in the year 6939, five thousand years after the first capsule was sealed.

New York State Pavilion: The New York State Pavilion is a historic world's fair pavilion at Flushing Meadows–Corona Park in Flushing, Queens, New York.  The New York State Pavilion was designed in 1962 for the 1964 New York World's Fair by architects Philip Johnson and Richard Foster, with structural engineer Lev Zetlin.

Retlaw Enterprises: Retlaw Enterprises, originally Walt Disney Miniature Railroad, then Walt Disney, Inc. (WDI), and then WED Enterprises (WED), was a privately held company owned by the heirs of entertainment mogul Walt Disney.  Disney formed the company to control the rights to his name and to manage two Disneyland attractions that he personally owned.  The name, Retlaw, is Walter spelled backwards.

Great Moments with Mr. Lincoln: Great Moments with Mr. Lincoln is a stage show featuring an Audio-Animatronic version of U.S. President Abraham Lincoln, best known for being presented at Disneyland since 1965.  It was originally showcased as the prime feature of the State of Illinois Pavilion at the 1964 New York World's Fair.  One year after its debut at the World's Fair, the show opened at Disneyland, where it has undergone several changes and periods of hiatus over the years.  Today "Great Moments with Mr. Lincoln" is an element of the Disneyland attraction The Disneyland Story presenting Great Moments with Mr. Lincoln, which opened in 2009.

Walt Disney World Railroad: The Walt Disney World Railroad (WDWRR) is a 3-foot ( ) narrow-gauge heritage railroad and attraction located within the Magic Kingdom theme park of Walt Disney World in Bay Lake, Florida, in the United States.  Its route is 1.5 mi in length and encircles most of the park, with train stations in three different park areas.  The rail line, constructed by WED Enterprises, operates with four historic steam locomotives originally built by Baldwin Locomotive Works.  It takes about 20 minutes for each train to complete a round trip on the WDWRR's main line.  On a typical day, the railroad has two trains in operation; on busy days, it has three trains.

Horizons (Epcot): Horizons was the name of a dark ride attraction at Epcot (then known as EPCOT Center), a theme park at Walt Disney World in Bay Lake, Florida.  Located on the eastern side of the "Future World" section of Epcot, the attraction used Disney's Omnimover conveyance system, which took guests past show scenes depicting visions of the future.  It is believed to be the sequel to Walt Disney's Carousel of Progress, an attraction in Tomorrowland at Walt Disney World's Magic Kingdom.  Horizons was the only attraction in "Future World" to showcase all of Epcot's "Future World" elements: communication, community interaction, energy, transportation, anatomy, physiology, along with man's relationship to the sea, land, air, and space.  The attraction officially opened on October 1, 1983, as part of Phase II of Epcot.  Horizons originally closed in December 1994, a little more than a year after General Electric had ended its sponsorship of the attraction.  Horizons re-opened in December 1995 due to the closure of two other attractions that were down for refurbishment in "Future World", Universe of Energy and World of Motion.  The attraction permanently closed on January 9, 1999, after which the attraction was dismantled and its structure demolished to make room for , a motion simulator thrill ride that opened on October 9, 2003.

Walt Disney's Carousel of Progress: Walt Disney's Carousel of Progress is an attraction located at the Magic Kingdom park at the Walt Disney World Resort.  Created by both Walt Disney and WED Enterprises as the prime feature of the General Electric (GE) Pavilion for the 1964 New York World's Fair, the attraction was moved to Tomorrowland at Disneyland in Anaheim, California as Carousel of Progress, remaining there from 1967 until 1973.  It was replaced in Disneyland by America Sings in 1974, and reopened in its present home in Walt Disney World Resort's Magic Kingdom in 1975.

Supporting paragraphs: There's a Great Big Beautiful Tomorrow Walt Disney's Carousel of Progress
Answer: There's a Great Big Beautiful Tomorrow