According to the passage, Kolchin's study asserts that which one of the following was true of Russian nobles during the nineteenth century? A. They agreed to the abolition of serfdom in the 1860s largely as a result of their having been influenced by the abolition of slavery in the United States. B. They became more directly involved in the management of their estates as a result of the rebellions that occurred in the previous century. C. They commonly agreed to at least some of the demands that arose out of the volnenie. D. They had relatively little direct contact with the serfs who worked on their estates. E. They hastened the abolition of serfdom by failing to devise an effective response to the collective nature of the serfs' rebellious activity.