The correct answer is: B. Heavy construction.
Railway projects are considered heavy construction because they involve the construction of large, complex structures that require a significant amount of material and labor. Railway projects also often require the use of specialized equipment and techniques, which can add to the cost and complexity of the project.
Light construction, on the other hand, refers to the construction of smaller, less complex structures. Light construction projects typically do not require the use of specialized equipment or techniques, and they can be completed relatively quickly and inexpensively.
Industrial construction refers to the construction of facilities for industrial use. Industrial construction projects can be either light or heavy, depending on the size and complexity of the facility being built.
Therefore, railway projects are considered heavy construction because they involve the construction of large, complex structures that require a significant amount of material and labor.