Why not A?

@lowe1sl, Lines 7-13 directly support answer choice (C) - the almost simultaneous abolition ...- a riveting coincidence that should have drawn more modern scholars to a comparative study of two systems of servitude.. . The fact that the demise of serfdom in both countries resulted from rebellions is independent from the fact that both institutions were abolished during the same decade, hence this is not the purpose of the author mentioning it.