Which statement best explains why carrying capacity estimates vary across studies?

• A. Global population size
• B. Climate
• C. Resource use per capita
• D. Geological activity

Answer: (C)

Carrying capacity is determined by how many individuals a given environment can support with its available resources, considering how much each person consumes and the technology that makes use of those resources. That's why estimates vary across studies: if a study assumes high resource use per person or less efficient technologies, the same resource stock yields a lower carrying capacity. Conversely, estimates rise when per‑capita consumption is lower or efficiency is higher. Global population size and climate influence resources, but they don’t directly drive the differences in estimates in the same way; geological activity tends to affect local conditions and is less explanatory for broad cross-study variation. So the key factor shaping differing carrying capacity estimates is how much resource use per person is assumed or observed.