Which of the following properties makes a material prone to breaking during impact?

Brittleness is a property that specifically indicates a material's tendency to break or fracture without significant deformation when subjected to stress, especially during an impact. This characteristic arises because brittle materials cannot absorb much energy during deformation; instead, they fail suddenly and often without warning.

In contrast, elasticity refers to a material's ability to return to its original shape after the load has been removed, which is not directly related to breaking under impact. Malleability and ductility are also properties associated with deformation, allowing materials to be shaped or stretched without breaking. Malleable materials can be hammered or rolled into thin sheets, while ductile materials can be drawn into wires. Both of these properties enable materials to withstand stresses and strains without fracturing, making them less likely to break upon impact.

Thus, the defining characteristic of brittleness is what makes certain materials prone to breaking during impact, as they lack the capacity to deform and absorb energy effectively.