The correct answer here would be the "Upon being treated with extreme xenia and welcomed graciously into the home of Menelaus, Paris took Helen home to Troy with him".
Xenia in essence is the ancient Greek concept of hospitality in which hospital was a reciprocal between the guest and the host in both material and other ways, such as the providing of help, favors, shelter. Paris broke these ancient rites and thus by their duty to Zeus, the Achaeans had to avenge this insult and the breach of xenia.
