What did the curies contribute to the field of radioactivity and nuclear chemistry?

Pierre and Marie Curie were awarded the 1903 Nobel Prize in Physics for their joint research in radioactivity. They proved that radioactivity does not depend on the arrangement of molecules in atoms, but that radioactivity originates from the atoms themselves. They also introduced two new elements: radium and polonium.

Ithink it’s 3 as the answer.