A loop or cross scavenged engine utilizes the motion of its pistons and a turbocharger to provide scavenging air. Which of the listed mechanical designs prevents the air under the pistons from being pumped back through the scavenge ports during the piston power stroke?

Correct Answer: Option C — Length of the piston skirt

In loop or cross-scavenged two-stroke engines using under-piston scavenging, the long piston skirt physically covers and seals the scavenge ports during the power stroke, preventing combustion pressure and air from being pumped backward into the scavenge receiver.