Final answer:
Refrigerated railcars allowed beef to be shipped more economically during the cattle boom.
Step-by-step explanation:
The statement that is true with regards to the cattle boom is option D) Refrigerated railcars allowed beef to be shipped more economically. The completion of the transcontinental railroad and subsequent railroad lines allowed cattle ranchers and businessmen to transport wild steers to eastern markets, making it profitable to sell them for a high price. Refrigerated railcars further revolutionized the cattle industry by allowing beef to be transported over long distances without spoiling, making it more economically viable.
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