Large national budget deficits do not cause large trade deficits. If they did, countries with the largest budget deficits would also have the largest trade deficits. In fact, when deficit figures are adjusted so that different countries are reliably comparable to each other, there is no such correlation.
If the statements above are all true, which of the following can properly be inferred on the basis of them?

The passage argues that there is no consistent relationship between national budget deficits and trade deficits once data are adjusted for proper comparison. This means that changes in one (the budget deficit) do not predict changes in the other (the trade deficit). Therefore, it logically follows that lowering a country’s budget deficit does not necessarily lead to a reduction in its trade deficit. The correct answer is therefore option (c) Reducing a country’s national budget deficit will not necessarily result in a lowering of any trade deficit that country may have.

Option (a) is unsupported; the passage never mentions trade restrictions. Option (b) is the opposite of what’s stated; it says comparisons are possible when adjusted. Option (d) introduces population, which is irrelevant to the argument.

Hence, (c) is the only valid inference.