Well it depends what they are in need of. They most commonly would want more land for their country to build and farm on. They may want land with fertile soil for farming. They may want the land because of it's geography, for example, for simple trade routes leading to and from the areas around north America (Canada, Mexico) etc.
It opened up the west by creating settlements, farms, cattle ranching, discovered many natural resources such as silver and gold.
The United Kingdom, and Spain
I agree with the person who answered this before me i’m pretty positive it’s D