Question

an economic exchange in which all sides agree to participate because they expect to benefit. voluntary trade economy international trade trade barrier

Explanation:

The question defines an economic exchange where all parties agree to participate as they expect benefits. "Voluntary Trade" matches this definition since it involves parties voluntarily engaging in trade for mutual benefit. "Economy" is a broader system, "International Trade" is trade between nations (not all voluntary exchanges are international), and "Trade barrier" restricts trade, not a beneficial exchange.

Answer:

A. Voluntary Trade