Final answer:
The correct answer is c) "Increased tensions and conflicts" due to westward expansion into western territories that led to conflicts with Native Americans and tensions with Mexico, particularly following the Mexican-American War.
Step-by-step explanation:
As the population grew in western territories, the answer is c) "Increased tensions and conflicts". Expansion into these territories often meant encroaching on Native American lands and increasing hostilities. The Mexican-American War aggravated relationships not only with Mexico but also with the broader region of Latin America. In the aftermath, American and Mexican populations experienced growing tensions as Hispanics were displaced and politically marginalized, particularly in Texas and California. Furthermore, westward expansion fostered debates over slavery following the Missouri Compromise and intensified the so-called "Indian problem," leading to government intervention and ultimately the forceful relocation of many tribes onto reservations.
The allure of cheap land in the West, agricultural challenges in the East, and political motivations all contributed to the dramatic population increase. Expansion was rooted in demographic, economic, and political pressures, with Americans clamoring for more land as the national population surged from around five million to over twenty million between 1800 and 1850. Such expansion also deeply influenced U.S. foreign policy and dictated political dynamics within the swiftly developing nation.