The carrying capacity (often denoted by the symbol K) is defined as the maximum population size of a species that a specific environment can sustainably support indefinitely given the available resources, such as food, water, and space. When a population reaches this limit, its growth typically levels off into a logistic growth pattern because the demand for resources matches the habitat's ability to supply them.

A. maximum population: While "carrying capacity" represents a maximum population size, the term "maximum population" itself is not the standard ecological term used to define the sustainable limit of a habitat based on resource availability.

B. working potential: This is not a standard ecological or biological term. It may be confused with biotic potential, which refers to the maximum reproductive capacity of a species under ideal conditions (the opposite of a limit).

D. operating capacity: This is typically a business or engineering term referring to the maximum output of a machine or system and does not apply to the biological limits of a natural habitat.