Why were the Swiss soldiers banned from singing songs from their homeland?

A、Thesongswouldmakethemlosetheirbattles.;
B、Singingsongswouldmakehomesicknessworse.;
C、It’sbelievedthatsingingsongscanleadtosoldiers’homesickness.;
D、Soldierswouldbetooimmersedinthebeautifulsongstofocusonthebattles.