Correct definition for syncopation is

The correct definition of "syncopation" is "placing an accent on a weak beat or between beats"

In music, syncopation involves a variety of rhythms which are in some way unexpected, making part or all of a tune or piece of music off-beat. More simply, syncopation is "a disturbance or interruption of the regular flow of rhythm": a "placement of rhythmic stresses or accents where they wouldn't normally occur."

photography had emerged as an elite art pursued by a few creative individuals for a few wealthy patrons. but now, said bauldelaire, it was succumbing to "the great industrial madness of our times." it was becoming a mass production industry that catered to middle-class tastes, including a taste for gadgetry. the stereoscope, the first 3d imaging system, had turned looking at photographs into parlor entertainment. a "thousand hungry eyes were bending over the peepholes of the stereoscope as though they were the attic-windows of the infinite.

your answer would be d.)