TOEFL Reading: ETS-TOEFL阅读机经 - DQ00WB5889B433M6L$

Why does the author include the information that "Moscow has been described as the first stopping and setting point in the northeast?" A. To explain why certain historically important areas near Moscow have fallen into a decline. B. To show why Moscow attracted populations of immigrants from lines located further to the northeast. C. To emphasize the importance of the location on Moscow in accounting for its growth. D. To challenge the idea that immigrants to Moscow came from only one direction.