A U. S. balance of trade surplus can result from

an increase in exports from the United States.

an increase in exports to the United States.

an increase in imports to the United States.

an increase in exports by foreign nations.

an increase in net exports by foreign nations.

From the research that I have done, exports to the United States increases the country's balance of trade. Possibly creating a surplus of goods.

The correct answer would be an increase in exports to the United States

Here is a good example of what you are trying to understand.

If a country exports a greater value than it imports, it has a trade surplus, positive balance, or a "favorable balance", and conversely, if a country imports a greater value than it exports, it has a trade deficit, negative balance, "unfavorable balance", or, informally, a "trade gap". A positive balance adds to gross domestic product, while a negative balance subtracts from GDP.