All of these answers could be true, I know for a fact that A is true, could you give more context?
Answer: an economic phenomenon where two parties each hold an item the other wants, so they exchange these items directly without any monetary medium!!
hope this helped :)
<span>The main impact of the completion of the Panama Canal was to increased world trade.</span>
<span>Abraham (earlier known as Abram; see Abram and Sarai) was born in what is today Iraq, in the region of the Euphrates River. It was there that the LORD told Abraham to leave, not create an inheritance for his righteous purpose (see The Journey From Ur Of The Chaldees and Don't Look Back). "12:1 Now ...</span><span>
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