Which of the following is a characteristic of a public good?
a. you must pay each time you use it.
b. it is typically maintained for private use.
c. the cost to build it is the same, regardless of how many people use it. d. you can apply for one if you plan to share it with the public.

C, I guess?  A park is a public good.  Roads are a public good.  The initial cost to build it is the same no matter how many people use it, but the more folks use it, the higher maintenance costs will be...

The business cycle is the periodic but irregular up-and-down movement in economic activity, measured by fluctuations in real gross domestic product (gdp) and other macroeconomic variables. a business cycle is typically characterized by four phases—recession, recovery, growth, and decline—that repeat themselves over time. economists note, however, that complete business cycles vary in length. the duration of business cycles can be anywhere from about two to twelve years, with most cycles averaging six years in length. some business analysts use the business cycle model and terminology to study and explain fluctuations in business inventory and other individual elements of corporate operations. but the term "business cycle" is still primarily associated with larger (industry-wide, regional, national, or even international) business trends.