SAT Question 271a5017: Text Structure And Purpose answer and explanation

English - Text Structure And Purpose - Function Of Specific Sentence
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The following text is adapted from Akwaeke Emezi’s 2019 novel Pet. Jam is a teenager who lives with her father, Aloe, and her mother, Bitter, who is a painter. Bitter finished the painting in the dark morning of a day—it was well past midnight when Jam heard the studio door creak open. She stared into the velvet black of her room and listened to her mother’s footsteps walking in her [mother] and Aloe’s bedroom. There was a weight thrumming through the floorboards in a low song, and that was how Jam knew the painting was done. Bitter’s feet were singing the news. ©2019 by Akwaeke Emezi
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Difficulty:Easy
Which choice best states the function of the underlined sentence in the text as a whole?