Final answer:
The most significant explanation of variations in living standards around the world is productivity, which is influenced by physical capital, natural resources, and technological knowledge.
Step-by-step explanation:
The one variable that stands out as the most significant explanation of large variations in living standards around the world is productivity. Productivity refers to the efficiency with which resources are utilized to produce goods and services. It is influenced by several factors, including physical capital, natural resources, and technological knowledge. These factors all contribute to the level of output a country can achieve.