The primary difference between a fixed budget and a variable (flexible) budget is that a fixed budget:

A. Includes only fixed costs, while a variable budget includes only variable costs

B. Is concerned only with future acquisitions of fixed assets, while a variable budget is concerned with expenses which vary with sales

C. Cannot be changed after the period begins, while a variable budget can be changed after the period begins

D. Is a plan for a single level of sales (or other measure of activity), while a variable budget consists of several plans, one for each of several levels of sales (or other measure of activity)

Answer: Option D