A、The longest street in the world. B、An advertisement on TV. C、A place of interest. D、A TV program. D

"Sesame Street" has been called "the longest street" in the world. That is because the TV program by that name can be seen in so many parts of the world. The program started in New York in 1969.
    In the United States more than six million children watch the program regularly. Parents praise it highly. Many teachers consider it a great help. (27) Research has shown that children from different backgrounds have benefited from watching "Sesame Street". Those who watch it five times a week learn more than the occasional viewers. In the United States the program is shown at different hours during the week in order to increase the number of children who can watch it regularly. In its American form " Sesame Street" is shown in nearly fifty countries. Three foreign shows based on "Sesame Street" have also appeared. In Spanish, Portuguese, and German, the program uses songs, stories, jokes and pictures to give children a basic understanding of numbers, letters and human relations.
    Why has "Sesame Street" been so much more successful than the other children’s shows? Many reasons have been suggested the educational theories of its creators, the skillful use of a variety of TV tricks and the famous stars on "Sesame Street", etc. (28) But the most important reason for its success may be that it makes every child watching it be able to find himself learning, and he wants to learn more.
26. What is "Sesame Street" according to the passage?
27. What do we learn from the research of "Sesame Street"?
28. What’s the most important reason for the success of the show?