The Nagpur plan is a classification system for roads that was developed in Nagpur, India. It categorizes roads based on their location and function. The correct answer for this question is option 'C' which means that roads are classified based on both location and function.

Location and Function as Classification Criteria:
1. Location: The Nagpur plan considers the location of the road as one of the criteria for classification. The location refers to the area or region where the road is situated. This criterion takes into account the surrounding land use, such as residential, commercial, industrial, or rural areas. The location of the road can have a significant impact on its design, capacity, and traffic flow.

2. Function: The function of a road refers to its purpose or role within the transportation network. The Nagpur plan recognizes that different roads serve different functions and have varying levels of importance. For example, some roads may primarily serve as arterial routes, carrying high volumes of traffic between major destinations. Others may serve as local access roads, providing connectivity within neighborhoods or smaller areas.

Classification of Roads:
Based on the combination of location and function, the Nagpur plan classifies roads into different categories:

1. National Highways: These are major roads that connect different states or important cities within the country. They serve as the backbone of the national transportation network and cater to long-distance travel.

2. State Highways: These roads connect important cities and towns within a state. They serve as a link between national highways and district-level roads.

3. District Roads: District roads connect various parts of a district, including towns, villages, and other important locations. They provide connectivity within a specific administrative region.

4. Village Roads: Village roads connect rural areas and provide access to villages and agricultural land. These roads play a crucial role in rural development and transportation of agricultural produce.

5. Urban Roads: Urban roads are further classified based on their location and function within a city or town. They include arterial roads, sub-arterial roads, collector roads, local access roads, and other specialized roads like ring roads or bypasses.

The classification of roads based on location and function helps in planning and designing the road network, allocating resources, and managing traffic efficiently. It allows for a systematic approach to meet the diverse transportation needs of different areas and ensures that roads are designed and maintained appropriately.