What Concept, Institution or Instrument Is Described by Each of the Phrases

Short Answer

What concept, institution or instrument is described by each of the phrases or sentences listed below?
a. Expenditures on capital goods or raw materials.
b. Current earnings retained in a business.
c. Funds left over out of current income after deducting current consumption expenditures.
d. An institutional mechanism for trading goods and services.
e. Collection of markets, individuals, institutions, laws and regulations through which financial services are produced and delivered.