Final answer:
Diane should paraphrase the sentence about the Big Dipper and provide proper citation to avoid plagiarism.
Step-by-step explanation:
The best way for Diane to use the sentence "It gets its name because it looks like a very large ladle" in her paper without plagiarizing is to paraphrase it and then cite the source. Paraphrasing involves rewriting the sentence in her own words, as in: "The constellation is named for its resemblance to an oversized scoop used in cooking". Diane must also include a citation in her paper according to the referencing style she has been asked to use, which could look something like this (CK-12 Foundation, edited for LibreTexts). By doing this, Diane shows that the ideas are not her own, avoiding plagiarism.