Final answer:
Coarse-grain soils include larger particles such as sand and gravel. So, among the options, 'D. Sand, gravel' correctly identifies the coarse-grain soil fractions.
Step-by-step explanation:
The question pertains to the classification of soil fractions based on grain size, specifically asking which options include coarse-grain soil fractions. Coarse-grain soils are composed of larger particles, which include sand and gravel. These particles have larger diameters and are therefore considered coarser than silt or clay. Silt has medium-sized particles, while clay has the smallest, fine particles.
According to the standard grain size classification utilized in geology and sedimentology, sand and gravel are designated as coarse soils, whereas silt and clay are considered finer soils. Thus, within the given options, D. Sand, gravel are the correct terms associated with coarse-grain soil fractions.