Final answer:
The first full color, feature-length animated film was Walt Disney's Snow White and the Seven Dwarfs, premiering in 1937.
Step-by-step explanation:
The first feature-length animated film in full color was a) Walt Disney's Snow White and the Seven Dwarfs. This classic film premiered in 1937 and marked a significant achievement in the history of cinema. It is often celebrated as a pioneering work in the field of animation due to its use of full color and fluid character animation. It was the first to utilize the full color, three-strip Technicolor process. Neither D. W. Griffith's The Birth of a Nation, Orson Welles’s Citizen Kane, nor Charlie Chaplin’s The Gold Rush are animated films, though they are significant in their respective rights for different historic reasons within the film industry.