The phenomenon described in the following poem cannot be explained by the straight-line propagation of light.

B, fishing for the moon in the water is futile, that is, the moon in the water is formed by the reflection of light, so B is wrong;

C, like a shadow, like a shadow, that is, the shadow is formed by the linear propagation of light, so C is correct;

D, the frog at the bottom of the well sees very little, which is formed by the linear propagation of light, so D is correct.

So choose B.