Why did america want control of the oregon country?

Oregon Country, 1846  Major Land Purchases Treaty of Paris Louisiana Purchase Red River Basin Florida Texas Annexation Oregon Country Mexican Cession Gadsden Purchase Alaska Hawaii States Emerge Expansion Concentration  Oregon Country was a portion of land between the Pacific Ocean and the Rocky Mountains in the northwest portion of the present-day United States. In 1818, the United States and Britain agreed to a "joint occupation" of Oregon, allowing citizens of both countries to settle there. Over the next several decades, American and British settlers came to Oregon for different reasons. The British came mostly for the fur trade, while Americans came to be missionaries or to start farms or larger settlements. By the 1840s, Americans outnumbered their British compatriots, and the fur trade was no longer as lucrative as it had once been. American expansionists — among them President James Polk — were increasingly looking to end the joint occupation and claim Oregon for America alone. Finding themselves in a weakened position, the British agreed to negotiate.

Negotiations between the United States and Britain over the Oregon Country began in the summer of 1845. Because any states that would eventually be formed out of the territory would be free states, anti-slavery Northerners were strongly in favor of acquiring as much of the territory as possible. America's first proposal was that the territory be divided roughly in half, with the boundary drawn at the 49th parallel. When the British rejected this offer, expansionist Northerners called for greater American aggression, using the slogan "Fifty-Four Forty or Fight!" ("Fifty-four Forty" referred to the latitude line marking the northernmost boundary of the territory.) Pro-slavery Southern Congressmen, however, made it clear that they would not support a war with Britain over the territory.

Britain did not want to go to war over the issue either, and in 1846, the two countries reached an agreement to divide the territory at the 49th parallel. Oregon Country would later become the modern-day states of Oregon, Washington, and Idaho, as well as portions of Montana and Wyoming.

Im pretty sure the answer is d.) is more densely populated.