题目内容：
根据以下内容，回答题。One of the greatest problems for those settlers in Nebraska in the last quarter of the previous century was fuel．Little of the state was forested when the first settlers arrived and it is probable that by 1880, only about one-third of the originally forested area remained, down to a mere 1 percent of the state’s 77,000 square miles．With wood and coal out of the question, and with fuel needed year-round for cooking, and during the harsh winter months for heating, some solution had to be foun
D．
Somewhat improbably, the buffalo provided the answer．Buffalo chips (干粪块) were found to burn evenly, hotly, and cleanly, with little smoke and interestingly, no odor, Soon, collecting them became a way of life for the settlers’ children who would pick them up on their way to and from school, or take part in competitions designed to counteract their natural reluctance．Even a young man, seeking to impress the girl he wanted to marry, would arrive with a large bag of chips rather than with a box of candy or a bunch of flowers．
What is the main topic of this passage?
A．The solution to the Nebraska settlers’ fuel problem．
B．Life in Nebraska in the late ninteenth century．
C．The imporance of the American buffalo．
D．Deforestation in Nebraska in the late nineteenth century．
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