The correct answer is: D. Pier footing
A pier footing is a type of foundation that is used to support heavy loads in sandy soils. It consists of a vertical column, or pier, that is embedded in the ground and a footing that spreads the load of the structure over a larger area. Pier footings are often used for the construction of flyovers, as they provide a stable foundation in unstable soils.
Strap footings are used to support loads that are not evenly distributed. They consist of a continuous concrete slab that is supported by a series of piers. Strap footings are often used for the construction of light-duty structures, such as single-family homes.
Raft footings are used to support large, heavy loads. They consist of a continuous concrete slab that is supported by a series of piers. Raft footings are often used for the construction of high-rise buildings and other large structures.
Combined footings are used to support two or more columns that are close together. They consist of a single concrete slab that supports both columns. Combined footings are often used for the construction of buildings with long spans, such as warehouses and factories.
Pier footings are the most common type of foundation used for the construction of flyovers in sandy soils. This is because they provide a stable foundation in unstable soils and can support heavy loads.