A、In 1890s. B、In 1923. C、In the early 1920s. D、In 1903. C细节题。文中最后一段提到：但是直到20世纪20年代初期，一个有效的声音系统才被开发出来。所以正确答案为C。

Hello, everyone! In today’s lecture, let’s talk about the cinema, and we’ll focus on the development process of cinema.
    The history of film spans over a hundred years, from the latter part of the 19th century to the present day. Motion pictures developed gradually from a carnival novelty to one of the most important tools of communication and entertainment, and mass media in the 20th century. Motion picture films have had a substantial impact on the arts, technology, and politics.
     (23)The first movie pictures were developed in 1890s by W. K. L. Dickson, an English man working in the USA. He called his system the kaleidoscope. It wasn’t the cinema we know at all. The pictures were very small and only one person at a time could watch. The earliest kaleidoscope used sound separately recorded on a phonograph, an ancestor of gramophone and record player.(24)But there were a lot of problems involved in getting the pictures and sound together, that is, synchronized. As a result, the kaleidoscope was popularized in its silent form. In the silent era of film, marrying the image with synchronous sound was not possible for inventors and producers, since no practical method was devised until 1923. Thus, for the first thirty years of their history, movies were silent, although accompanied by live musicians and sometimes sound effects and even commentary spoken by the showman or projectionist.
    The same principle was developed by the French men called cinematographe, and between 1895 and 1900 they succeeded in exporting it to other parts of Europe, to India, Australia and Japan. The cinematographe used a large screen, but the film was shown very short, only but a minute long. Like the popularized kaleidoscope, it was a silent system.
    The early films were made with fixed cameras. This greatly limited what could be achieved. So an important advance was the use of a moving camera which could turn from side to side and also move about to follow the action. The Great Train Robbery was the first important experiment in the use of moving camera. It was made in 1903 by an American and lasted eight minutes. In the following years, films became much longer and screens larger. Other refinements were introduced, too.(25)But it was not until the early 1920s that an effective sound system was developed. Leader Forrest, another American, found way of photographing sound waves which accompanied the action. This eliminated the major problem of sound-picture synchronization. Although the first company to make talkies rather than silent movies used the system quite different from the Forrest’s, it was his which created the general norm. An odd consequence of having sound was that for a few years the camera once again had to be fixed. This was because there were sounds proved to reduce the noise of the mechanism and the soundproofing was so bulky that they could not easily move about. Once again for a time, the cinema looked like the theatre.
Now listen to the following recording and answer questions 23 to 25.
23. Who developed the first movie pictures?
24. Why was the kaleidoscope popularized in silent form?
25. When was an effective sound system developed?