Answer:
A) It reduced the spread of slavery.
Step-by-step explanation:
The Louisiana purchase led to a growth in the territory of the U.S, almost doubling the size of the country. The purchase reduced the spread of slavery since it banned slavery in the area.
B cannot be the correct answer because the purchase strengthened the U.S. but didn't help prevent the Civil war.
C is not correct because the purchase didn't lead to the construction of roads and canals.
D is not correct because the Louisiana Purchase did not have an influence in breaking apart the U.S.