单项选择题The author writes the development of geology to demonstrate ______.
单项选择题The growth of specialization in the 19th century might be more clearly seen in sciences such as ______.
单项选择题We can infer from the passage that ______.
单项选择题The direct reason for specialization is ______.
单项选择题The last sentence of the first paragraph most probably implies that it is ______.