It's 3. All the other answers are opinons and not provable by fact.
My best guess for the answer to this question is that the listener in My Last Duchess interacts with the speaker while the listener in Life in a Love does not. In My Last Duchess, a rich duke is having a conversation with a man about a portrait of his late wife while negotiating a deal to marry a new woman. Life in a Love is about a man's reaction to a woman possibly leaving him. In the first poem, there seems to be a more active conversation going on. I hope this helps. None of the other answers seem as relevant, so I think this is the right one.
Your answer ir c............
Because he sacrificed his good friend to ensure that Romans would not be enslaved.
