Among the following countries, where did the idea of 'Social Market Economy' emerge in 1950s?

The idea of the 'Social Market Economy' (Soziale Marktwirtschaft) emerged in Germany as a foundational economic model for rebuilding society after World War II. The term was coined in the late 1940s by Alfred Müller-Armack, a German economist associated with the 'ordoliberal' Freiburg School. It became the leading political and economic ideology of West Germany in the 1950s, famously championed by Ludwig Erhard, the Minister of Economics and later Chancellor. This model sought a 'middle way' by combining the efficiency of a free market economy with social safeguards to ensure social justice and security [1]. It is credited with driving the 'Wirtschaftswunder' or 'German economic miracle' during the 1950s, distinguishing West Germany's path from the more interventionist planning seen in other European nations at the time [1].

Sources

1. [1] https://www.lse.ac.uk/Economic-History/Assets/Documents/WorkingPapers/Economic-History/2008/WP113.pdf