Which sentence uses syntax for emphasis?
it is easier to do a job right than to explain why you didn't.—martin van buren
the price of freedom is eternal vigilance. .thomas jefferson
the truth is that all men having power ought to be mistrusted. .james madison
never was she so enchanting as at this time, when she recalled the sunshine of her smiles and spent them upon us.—shelley, frankenstein

Never was she so enchanting as at this time, when she recalled the sunshine of her smiles and spent them upon us.—Shelley, Frankenstein

Explanation: The last option is the one that uses  syntax for emphasis. In fact, the strategy used by the writer to give more emphasis is called "Inversion". Inversion means that the writer puts the verb before the subject. Even though inversion is mainly used to ask questions, it is sometimes used as a way of emphasizing a structure. In the example given the writer uses syntax to emphasis the following phase: "Never was she so enchanting as at this time" (the verb WAS is before the subject SHE)

intonation based on rhythm.

which is the following what are you asking?