About Lighting and reflection of the trailer: which statement is WRONG?

The red TRIANGULAR reflectors belong at the REAR; at the front are white (non-triangular) retroreflectors.

White retroreflectors belong at the FRONT; at the rear are red triangular reflectors.

A rear fog light is optional on a trailer.

This trailer itself must always have a rear fog light.

Explanation

Book p.232 - 1 red rear fog light is in the trailer's minimum equipment requirements; it is always required, not optional.