Which of the following contains a formal sentence definition?
a. Stress is a measure of the internal reaction between elementary particles of a material in resisting
separation, compacting, or sliding that tend to be induced by external forces.
b. The resisting forces within the material are made up of continuously distributed normal and
tangential forces that are of varying magnitude and direction and act on elementary areas throughout
the material.
c. These forces can be distributed uniformly or nonuniformly and can be categorized as tensile,
compressive, or shearing, according to the straining action.​