A

A (both worked to create the first atomic bombs for the USSR) is correct.

Explanation:

Julius and Ethel Rosenberg were a couple that was arrested and found blameworthy of espionage for the Soviet Union during the second Red Scare. Their role as spies was to help the USSR acquire enough information on the American atomic bomb to speed up the Soviet’s production of it. They were convicted on the testimony of their comrades, David Greenglass and Harry Gold.

The Rosenberg trial caused dismay in many countries of the world, with many people protesting their conviction as they were merely civilians. The book “Executing the Rosenbergs: Death and Diplomacy in a Cold War World” by Lori Clune follows their story closely and explains in further detail the reasons for which the Rosenbergs were executed.

Protest Against the Execution of the Rosenbergs.
Protest Against the Execution of the Rosenbergs (Source: https://www.biography.com)