The Penetration of the Wave Function Beyond the Edges of the Finite

The penetration of the wave function beyond the edges of the finite square-well potential shown in the figure

A) indicates that there is some small probability of finding the particle outside the well.
B) forces us to conclude that E - U₀ is negative in these regions.
C) suggests that these regions are classically forbidden.
D) is unexplainable classically.
E) is described by all of the above.