What is an arrangement between countries to allow free trade between members called?

If policymakers in an open economy want to increase the wealth of their citizens, should they seek to increase saving, or to increase investment? Explain

What will be an ideal response?

Which of the following is NOT subject to a network effect?

A) the layout of the keys on your keyboard B) rotating your tires every six months C) using a fax machine D) purchasing a new high-definition DVD player