阅读理解。阅读下列短文, 从给的四个选项 (A、B、C和D) 中, 选出最佳选项。
The number of speakers of English in Shakespeare's time is estimated (估计) to have been about five million.Today it is estimated that some 260 million people speak it as a native language，mainly in the United States，Canada，Great Britain，Ireland，South Africa，Australia and New Zealand.In addition to the standard varieties of English found in these areas，there are a great many regional and social varieties of the language as well as various levels of usage that are employed both in its spoken and written forms.
