Which statement defines externality?

A.  

It is a change in demand brought about by factors other than price.

B.  

It is the external factors that cause a rise in the supply of goods or services.

C.  

It is the external factors that cause a decrease in the supply of goods or services.

D.  

It is the impact of production and consumption on unrelated third parties.

well we can't tell you because we cant see the time give a screen shot or something.