What was Thomas Jefferson’s greatest contribution to westward expansion and how did it affect the US

Thomas Jefferson acquired an interest in western exploration early in life. ... While president, Jefferson successfully acquired the Louisiana Territory from France in 1803 and sent the Lewis and Clark Expedition (1803–1806) on a mapping and scientific exploration up the Missouri River to the Pacific.

That westward expansion was greatly aided by the completion of the Transcontinental Railroad in 1869, and passage of the Homestead Act in 1862.

In the mid-19th century, the quest for control of the West led to the annexation of Texas and the Mexican–American War. ... This expansion led to debates about the fate of slavery in the West, increasing tensions between the North and South that ultimately led to the collapse of American democracy and a brutal civil war.

Explanation:

the correct answer is d

the correct answer option is: weapons.

explanation:

tensions rose as the two opposing superpowers competed for 'weapons'.

referring to the cold war (1945-1991), the two superpowers, usa and ussr, experienced a phase of struggle and conflict with each other. these two superpowers considered each other as a threat to their survival and thus opted for policies to strengthen their positions.

the two superpowers never went to war with each other directly but competed for weapons to preserve their positions.