They had as few rights as slaves.
Russian serfs were pretty much Russian servants, and they were generally treated based on their master (similar to slaves). If their masters were more lenient, they had a "nicer" master. If the master mistreated the serfs, then it would be pretty much the same as most slave owners.
It is not B, because they didn't have to pay much tax, as they owned no property.
It is not C, because they were contracted to stay on the land until their debt is repaid.
I'm not sure what time period it is for this question, so I wouldn't check D unless you know for sure what the answer is.
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The Decembrist Uprising was the uprising in which revolutionaries failed to overthrow and coup d'tat the government.
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