单选题 The author indicates explicitly that which of the following records has been a source of information in her investigation?

A、 United States Immigration Service reports from 1914 to 1930.
B、 The volume of cotton exports between 1898 and 1910.
C、 The federal census of 1910.
D、 Advertisements of labor recruiters appearing in southern newspapers after 1910.

【正确答案】 C

【答案解析】[注释]细节理解题。本题问：作者明确表示，下面哪一记载是她调查的信息源?第2段第3句写道；“1910年60多万黑人，或曰10%的黑人劳工声称他们从事’制造业或机械化职业’，联邦人口普查范围基本上包括了整个工业部门。”可见，1910年联邦人口普查的资料是作者调查的信息来源，故应选[C)。