Which of the Following Is the Definition of a Leading

Which of the following is the definition of a leading indicator?

A) It is an informal way of measuring the purchasing power parity between two currencies.
B) It is a measurement of consumer confidence,which is defined as the degree of optimism about the state of the economy.
C) It is an economic indicator found by adding the unemployment rate to the inflation rate of an economy.
D) It is an indicator to measure changes in the price level of consumer goods and services purchased by households.
E) It is an objective measure that accurately predicts future labor demand.