A spark from the fire had set light to a rug.

从火炉迸出的火星点燃了地毯。

《牛津词典》

A single spark can start a prairie fire.

星星之火，可以燎原。

《新英汉大辞典》

The single spark that started the prairie fire suggests the answer.

引发燎原之火的火花暗示了答案。

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How did that fire spark the massive explosion that tore through the northern part of town -- killing 14 people, including nine first responders, and injuring hundreds of others?

CNN: Powerful Texas blast left nearly 100-foot-wide crater

Inside, the flat was rigged with a tripwire connecting the front door to chemicals that, when mixed, would spark a fire, he testified.

BBC: Batman suspect James Holmes 'set booby-traps' in flat

So my side of your life is that side that says John Doe, carve out a career you can control using my real estate development knowledge and your unique skills along with that spark of entrepreneurial fire inside of you.

FORBES: It's A Dirty Business: The Green Entrepreneurs Who Create Treasure (And Profit) From Trash