Which of the following systems is designed to carry the vertical load of the structure?

The system designed to carry the vertical load of the structure is piling. Piling consists of long, slender, column-like elements driven deep into the ground to provide foundational support, typically transferring the weight of the structure to deeper, more stable soil layers or bedrock. This method is particularly advantageous in situations where the surface soil is too weak to support the structure itself, ensuring that the vertical load is adequately supported and preventing settlement or structural failures over time.

In contrast, underpinning is a technique used to strengthen footing or foundations but does not directly carry the vertical loads as it primarily supports existing foundations by extending them to more stable soil. Cribbing and tie-backs are primarily used for lateral support and stabilization in construction but do not bear vertical loads. Cofferdams are temporary structures used to hold back water during construction activities and aren't designed for carrying vertical loads. Each of these systems serves distinct functions in construction, making piling the appropriate choice for sustaining vertical loads.