If you want to analyze the exact word choice of a source in your essay, you should use the method of close reading. Close reading involves analyzing a text in detail, looking at its tone, style, language, and structure, to gain a deeper understanding of its meaning and implications. In order to perform a close reading, you should read the text several times, take notes of key points, and identify the specific words and phrases that are particularly important or impactful. Afterward, you can use this close analysis to support your own claims and arguments in your essay.