Hi, b and c are taking different positions on what the author of a would think. B says that the first author would agree with the second, while c says that the first author must not have known about the research the second author cites.
Our task then is to see if there is any reason to think they would agree, or if there is any reason to think that the info in passage b would be critical to the author of As argument- likely by disproving or modifying As argument.
