When going down a steep grade with a doubles or triples combination, you should:
a.Use a lower gear and apply brakes intermittently using proper braking technique
b.Ride the brakes continuously to maintain a steady speed
c.Shift into neutral to save fuel
d.Apply only the trailer brakes
Explanation
When descending a steep grade with doubles or triples, use a low gear selected before the descent and apply brakes using the proper snub braking technique: apply brakes to reduce speed, release to allow cooling, then repeat. Continuous braking causes brake fade.