Final answer:
Rosalind's quote comparing love to madness encapsulates the idea that love can drive individuals to folly, supporting the theme that love induces foolish behavior.
Step-by-step explanation:
The lines spoken by Rosalind that best support the theme that love can lead people to act foolishly are: "Love is merely a madness, and, I tell you, deserves as well a dark house and a whip as madmen do" (lines 37-38). This quote reflects the notion that love can make individuals lose their reason and behave in irrational ways, a sentiment echoed throughout literature and history.