Questions: Tchaikovsky's Romeo and Juliet was based on a play by: A. William Shakespeare. B. Henry Wadsworth Longfellow. C. Emily Dickinson. D. Walt Whitman.

The answer is A. William Shakespeare.

Tchaikovsky's "Romeo and Juliet" is a symphonic poem based on the play "Romeo and Juliet" by William Shakespeare. This play is one of Shakespeare's most famous works and has inspired numerous adaptations in various art forms, including music.

Henry Wadsworth Longfellow was an American poet known for works such as "Paul Revere's Ride" and "The Song of Hiawatha." He did not write "Romeo and Juliet."

Emily Dickinson was an American poet known for her unique and innovative style. She did not write plays, and "Romeo and Juliet" is not one of her works.

Walt Whitman was an American poet best known for his collection "Leaves of Grass." He did not write "Romeo and Juliet."