The correct answer is: C. 1, 2 & 3
Economic overheads are the costs of providing infrastructure and services that are essential for economic activity, but which do not directly produce goods or services. They include things like roads, railways, schools, hospitals, and power plants.
Roads and railways are essential for the movement of goods and people, which is necessary for economic activity. Schools provide education, which is necessary for a skilled workforce. Sanitary facilities help to prevent the spread of disease, which is necessary for a healthy workforce. Hospitals provide healthcare, which is necessary for a healthy population.
Option A is incorrect because it only includes roads and railways. Option B is incorrect because it only includes roads and railways, and schools. Option D is incorrect because it includes all of the options, but also hospitals.