By no stretch of the imagination means not in any possible way. The correct answer is this meaning because the expression is used figuratively, not only by its literal words.

Examples:

• He is by no stretch of the imagination an expert.
• In an HSC essay, By no stretch of the imagination can express this meaning: not in any possible way.
• When this expression appears in a passage, connect By no stretch of the imagination with the idea of not in any possible way.