Limits to Growth focuses on which of the following Environmental Concerns?

The correct option is Depletion of the Earth’s resources.

Explanation:
The seminal 1972 report The Limits to Growth, commissioned by the Club of Rome, utilized computer simulation models to study the long-term interactions and consequences of exponential growth in five major global subsystems: world population, industrialization, food production, consumption of non-renewable resources, and pollution.

Among the given choices, the primary environmental concern that directly aligns with the core thesis of the report is the depletion of the Earth's non-renewable resources. The model demonstrated that if the trends in resource consumption and economic development continued unchecked, the physical limits of our planet would be reached within a century, leading to a sudden and uncontrollable decline in both population and industrial capacity.