Dispersion-strengthened composites are a type of composite material that consists of a metal matrix with small particles of another material dispersed throughout. These small particles act as obstacles to dislocation motion and enhance the strength and hardness of the composite.

a) Particulate composites:
Particulate composites are a type of composite material where small particles or reinforcements are dispersed within a matrix material. These particles can be ceramic, metallic, or organic in nature. In dispersion-strengthened composites, the small particles act as the strengthening phase and are dispersed within the metal matrix. Therefore, particulate composites can be dispersion-strengthened composites.

b) Laminar composites:
Laminar composites are composed of layers or sheets of different materials stacked together. These layers can be bonded together using adhesives or mechanical fasteners. While laminar composites can have improved mechanical properties, they do not typically involve the dispersion of small particles within a matrix material. Therefore, laminar composites are not dispersion-strengthened composites.

c) Fiber reinforced composites:
Fiber reinforced composites consist of a matrix material, commonly a polymer or a metal, reinforced with fibers. The fibers can be made of materials such as carbon, glass, or aramid. These fibers provide the strength and stiffness to the composite, while the matrix material provides support and protection. While fiber reinforced composites can have enhanced mechanical properties, they do not involve the dispersion of small particles within a matrix material. Therefore, fiber reinforced composites are not dispersion-strengthened composites.

d) Short-fiber discontinuous composites:
Short-fiber discontinuous composites are composed of a matrix material with short fibers dispersed throughout. These fibers are randomly oriented and typically have a length-to-diameter ratio of less than 100. While short-fiber discontinuous composites can have improved mechanical properties, they do not involve the dispersion of small particles within a matrix material. Therefore, short-fiber discontinuous composites are not dispersion-strengthened composites.

In conclusion, the only type of composite material listed that can be considered a dispersion-strengthened composite is a particulate composite.