Thanks, that's what I suspected.
In that case we need a broader definition of "nacionais" in the mouseover text and a different English translation for the answer. The current English translation is just bad. I got the answer right because I guessed that's what would be accepted, but I didn't learn anything from this exercise. (But again, I did from your comment here, so thanks for that!).
In English, you would usually name the country. We talk of buying products made in the USA, for example. Or we might say we buy American products. In Puerto Rico, we speak of "productos hechos en Puerto Rico". I can understand people in other cultures speaking of "national products" to convey the same idea.
Interesting..... this sentence seems (one of many) duplicated from DL's Italian course (or maybe it's vice versa) without realizing that the correct English way of saying this is, as EsteveTheSteve says, domestic products. National product is a term in Economic science indicating the total value of goods produced and services provided by a country over the course of one year.