Which of the following accurately describes variable costs?

Variable costs are indeed directly related to patient output, making this choice the correct one. In a healthcare context, variable costs fluctuate based on the level of services provided or the number of patients treated. For instance, if a hospital sees an increase in patient admissions, costs for supplies, staff overtime, and medications may rise correspondingly. This relationship highlights the nature of variable costs, which grow or shrink in response to demand or usage levels.

Other options do not accurately reflect the definition of variable costs. Constants in budgeting refer to fixed costs, which do not change with the level of activity, thus making option about constants incorrect. Non-essential expenses can pertain to variable costs in some contexts, but not all variable costs are considered non-essential; many are critical for operations. Similarly, fixed costs, by definition, remain constant regardless of output levels, contrasting with the variable nature of the costs outlined in the correct answer.