Final answer:
The line from "Sonnet 30" that uses exaggeration is "They stretched in never-ending line."
Step-by-step explanation:
The line from "Sonnet 30" that effectively uses the technique of exaggeration is:
They stretched in never-ending line
This line uses exaggeration to describe the length of the line, emphasizing its seemingly infinite nature. By using the phrase "never-ending," the speaker creates a vivid image of a line that goes on indefinitely. This exaggeration helps to convey the immensity and significance of the line being described.