To ensure that a beach nourishment project remains effective for as long as possible, the response that would generally be most beneficial is:
Large, coarse grains of sand should be used.
Using larger, coarser grains of sand can help the beach withstand wave action better than finer sand, as they are less likely to be washed away quickly. While other factors like vegetation and the method of dredging can also play a role in beach stability, the grain size of the added sand is crucial for long-term maintenance of the beach.