Answer:
the United States acquired b) Louisiana at no cost.
Explanation:
Here's a breakdown of the other options:
a) Alaska: The United States purchased Alaska from Russia in 1867 for $7.2 million, known as the Alaska Purchase.
c) Hawaii: The United States annexed Hawaii in 1898, but it wasn't entirely a free acquisition. While there was no formal purchase price, the United States compensated the Hawaiian monarchy with $20 million to quell potential opposition.
d) Puerto Rico: The United States gained control of Puerto Rico following the Spanish-American War in 1898 through the Treaty of Paris. While not directly purchased, it wasn't acquired at no cost.
