The addition of "under God" to the Pledge of Allegiance and adopting "In God We Trust" as the national motto in the 1950s was largely symbolic and reflected a complex set of cultural and political factors. The correct answer to your question is A. that there was a religious resurgence
During the 1950s, the United States was engaged in the Cold War with the Soviet Union, and there was a perceived ideological conflict between the atheistic communism of the Soviet Union and the religious values of the United States.
In this context, there was a cultural and political emphasis on the United States as a nation under God to distinguish it from the perceived godlessness of communism.
The religious language added to the Pledge of Allegiance and the national motto was seen by many as a way to emphasize the nation's commitment to religious values, morality, and the idea of a higher power.
This period witnessed a rise in religious sentiment, and the addition of these phrases was part of a broader cultural shift that included increased attendance at religious services, a revival of interest in religious organizations, and a general sense of religiosity.
Therefore, the correct interpretation is that the addition of "under God" and "In God We Trust" signified a religious resurgence during the 1950s.