The finding that korsakoff's syndrome impairs declarative memory is most consistent with the fact that

I believe the answer is: Lesions that affect the hippocampus would be most consistent with memory impairment

Hippocampus had the function to consolidate the information that we get from the short-term memory into the long-term memory. When there is a lesion on this area, the consolidation process would be distrubed, whcih tend to make us unable to put new information that we just learn into long-term memory.