Which two countries border Lake Ontario?

The correct response identifies the two countries that share a border with Lake Ontario, which are Canada and the United States. Lake Ontario serves as a significant geographical boundary between these two nations, with the northern shore located in Canada and the southern shore in the U.S.

This international border is important not only for geographical purposes but also for trade, transportation, and environmental management.

Understanding that both Canada and the United States are the only nations bordering the lake helps clarify why the other options are incorrect. France is not adjacent to Lake Ontario; Mexico, while a neighboring country to the United States, does not border the lake at all.