Question

Which of the following European land empires expanded its territory most aggressively in the sixteenth and early seventeenth centuries?

Answer 1

While you did not provide a list of possible answers. One can deduce, based on the time period, about what European lands we're talking about.

You're talking about the sixteenht and seventeenth centuries. This means that you're talking about the age of exploration.

Knowing this, we can safely say it's most likely that Spain and Portugal were the nations that most expanded their lands.