The correct answer is D, because that is the only sentence written in the active voice, the rest are written in the passive voice.
<span> Curie, a two-time Nobel Prize recipient and physics professor at the Sorbonne (a college of the University of Paris), presented this speech at Vassar College in Housekeeping, New York, on May 14, 1921. The speech, preserved in print as no. 2 of Vassar's Ellen S. Richards Monographs series, centers on what Curie called "the somewhat peculiar conditions of the discovery of radium" and her view that "the scientific history of radium is beautiful." The speech is provided online at the Gifts of Speech Web site, by Liz Linton, site director; and electronic resources and serials librarian in Cochran Library, Sweet Briar College, Virginia.</span>
