Question

what was the commonality between becquerel and the curies in terms of their work?
polonium
radium
uranium
cesium

Explanation:

Henri Becquerel discovered radioactivity in uranium - salts. Marie and Pierre Curie also did extensive work on radioactive substances, and uranium was central to their early research on radioactivity. Polonium and radium were discovered by the Curies but not directly related to Becquerel's initial discovery. Cesium has no connection to their common work in radioactivity.

Answer:

uranium