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

The white retroreflectors of a trailer belong at the rear.
✓ Orange retroreflectors belong on EACH SIDE; at the front are white retroreflectors.
A trailer only needs a fog light if it was put into service after 31 December 1997.
The red triangular reflectors of a trailer belong at the front.

Correct answer: Orange retroreflectors belong on EACH SIDE; at the front are white retroreflectors.

Explanation

Orange retroreflectors belong on EACH SIDE; at the front are white retroreflectors.

White retroreflectors belong at the FRONT; at the rear are red triangular reflectors. Red rear, white front.
This trailer itself must always have a rear fog light. The only exception is if the TOWING vehicle itself has no fog light. The law does contain a date nuance for older heavy trailers, but the exam follows the book: treat the rear fog light as always mandatory.
The red TRIANGULAR reflectors belong at the REAR; at the front are white (non-triangular) retroreflectors.