If a trailer wheel on a doubles/triples skids, which problem is most likely to occur?

Answer: D — You will have a trailer jackknife

When a wheel on one of the trailers loses traction and slides, that axle can no longer steer or control the trailer effectively. In a doubles or triples setup, the trailers are tied together, so a skid on one unit creates a sideways pull or push that the rest of the rig can’t counter quickly. That sideways movement pivots around the connection points (the kingpin and the couplings), causing the towed trailers to swing relative to the tractor. With the linked trailers, this swinging accelerates into a sharp angle between the units—the classic jackknife. The result is more than a simple skid; the whole combination folds in on itself. Other outcomes like a skid simply lasting longer or braking overheating are less direct consequences of a single-wheel skid in a multi-unit combination, whereas the linkage geometry makes a trailer jackknife the most likely and dangerous result.