In an artwork using perspective, at which point do the orthogonal lines in the work merge? in an artwork using perspective, the orthogonal lines in the work merge at the point.

In an artwork using perspective, the orthogonal lines in the work merge at the vanishing point. 

These lines are used to maintain a perspective which means giving the art a realistic view of the object/s. The vanishing point is a point that stands at eye-level on the horizon. There can be either one or more vanishing points and thus derive the terms “one-point perspective”, “two-points perspective”, etc. 

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.

(a) i got it right on the test