A. The first is a consideration raised to support a conclusion,
which is disputed in the argument; the second is a fact that goes against the intermediate conclusion of the argument. -> The second doesn’t necessarily directly go against the intermediate conclusion. Moreover the intermediate conclusion is not exaclty disputed in the argument, instead an alternate conclusion is presented. (It may happen that the customers favouring elderly people serving them still might not outweigh the employee attrition.) Close answer tbh.
B. The first is evidence used to support a conclusion that goes against the main conclusion of the argument;
the second is a fact that the argument seeks to explain. -> Even if we consider that the first part is somewhat right, the second part looks incorrect. The argument doesn’t try to explain the highlighted part. Instead it tries to explain the main conclusion: "their employment is likely to become an industry-wide feature."
C. The first is an objection raised to a proposed solution;
the second is evidence that casts doubt on the accuracy of that objection. -> The second does not cast doubt on the highlighted part in the first.
D. The first is a circumstance cited to support a conclusion; the second is a consideration that goes in favor of a position not supported by that conclusion. -> Correct! The second supports position which is not supported by the former conclusion (which states that the new move of employing older people will not be beneficial). Here take a note that the second part doesn’t attack the intermediate conclusion directly. Instead it just supports a different position. E.
The first is a judgment that supports the main conclusion drawn by the author; the second is a claim that supports the intermediate conclusion. -> The first is not the main conclusion. The main conclusion is: "their employment is likely to become an industry-wide feature."