Which play was written by William Shakespeare?

A Midsummer Night's Dream is indeed a play written by William Shakespeare, one of the most prominent playwrights in English literature. This comedy, believed to have been written in the late 16th century, explores themes of love, dreams, and the complexities of human relationships. It features a lively mix of characters, including fairies, noble Athenians, and wandering tradesmen, and is well-known for its enchanting portrayal of love and magic.

The other works listed belong to different authors and genres. Pygmalion is a play by George Bernard Shaw, focusing on themes of class and language. War and Peace is a historical novel by Leo Tolstoy that delves into the lives of various characters during the Napoleonic Wars. The Three Musketeers is a novel by Alexandre Dumas, set in 17th-century France, chronicling the adventures of a young man who becomes embroiled in a plot involving swordplay and political intrigue. Thus, A Midsummer Night's Dream is uniquely associated with Shakespeare, distinguishing it from the other options in the question.