"Uncle Tom’s Cabin was often produced as a play, so that many people who did not read the book saw it as a powerful stage drama. Although, especially at first, white actors usually played the African American parts in blackface, some productions starred African American actors and singers. At least seven silent-film versions of Uncle Tom’s Cabin had been made by 1927. The 1970 film version stars African American actress Eartha Kitt."

Which sentence is the main idea?

Although, especially at first, white actors usually played the African American parts in blackface, some productions starred African American actors and singers.

Uncle Tom’s Cabin was often produced as a play, so that many people who did not read the book saw it as a powerful stage drama.

At least seven silent-film versions of Uncle Tom’s Cabin had been made by 1927.

The 1970 film version stars African American actress Eartha Kitt."