Wages are higher in Country X than in Country Y. If the countries decide to trade, then who will benefit?

Only the country that can produce the product at a lower opportunity cost will benefit.

Both countries can benefit regardless of the products traded.

Only the country that can produce the product more efficiently will benefit.

Neither country can benefit unless one knows the product that is traded.

Both countries will benefit, but only if a trade agreement for specific products is made by their respective governments.