Concept:
A vertical photograph is intended to have its optical axis truly vertical, but small unavoidable tilts occur. A photograph is treated as a tilted photograph when this tilt angle is small but non-zero.
Step 1:
In photogrammetry a vertical photograph practically has a tilt of up to about 3°. A tilt of around 3° is the small minimum inclination associated with a tilted vertical photograph, whereas larger angles correspond to oblique photographs.
Step 2:
Among the choices, values like 13°, 33° and 33.33° are too large to represent the minimum tilt of a near vertical (tilted) photograph; the appropriate small minimum inclination is 3°.
Answer: Option (2) — 3°.