Question

although leo szilard conducted the first atomic research, he was opposed to
testing atomic bombs in new mexico.
dropping atomic bombs on japan.
testing the atomic bomb on a deserted island.
sending a naval blockade to force japan to surrender.

Explanation:

Leo Szilard, a key figure in early atomic research, was deeply concerned about the humanitarian impact of atomic bombs. He opposed using them on civilian - populated areas. Dropping atomic bombs on Japan (Hiroshima and Nagasaki) was a major act of warfare with massive civilian casualties. Testing in New Mexico (Trinity test) was a scientific - military test (though with ethical concerns too, but Szilard's main opposition was to the combat use). Testing on a deserted island was not a main focus of his opposition. A naval blockade was a different military strategy.

Answer:

dropping atomic bombs on Japan.