Traffic requirements:
- One of the major factors that influence road alignment is the traffic requirements.
- The alignment of a road should be designed to accommodate the anticipated traffic volume and type of vehicles that will use the road.
- Factors such as design speed, lane width, and sight distances are determined based on the traffic requirements.
- The alignment should provide safe and efficient movement of vehicles, taking into consideration factors such as overtaking opportunities, curves, and grades.

Stability of hill slopes:
- The stability of hill slopes is another important consideration in road alignment.
- When a road is constructed on hilly terrain, the stability of the slopes along the road corridor is crucial.
- Slopes should be stable enough to prevent landslides or slope failures that could potentially disrupt the road or pose a hazard to users.
- The alignment should avoid steep slopes, areas prone to erosion, and areas with weak or unstable soil conditions.
- Proper slope stabilization measures may need to be implemented to ensure the long-term stability of the road.

Number of cross drainage works:
- Cross drainage works are structures that allow water to pass through or under a road.
- These include culverts, bridges, and other hydraulic structures.
- The number and type of cross drainage works required along the road alignment depend on the natural drainage patterns of the area.
- Streams, rivers, canals, or other water bodies that intersect the road alignment need to be properly accommodated to prevent flooding or obstruction of the road.
- The alignment should be designed to minimize the number of cross drainage works while ensuring effective drainage and water flow.

All of the above:
- The correct answer to the question is option 'D' - all of the above.
- Road alignment is influenced by a combination of traffic requirements, stability of hill slopes, and the number of cross drainage works.
- These factors need to be carefully considered and incorporated into the road design to ensure safe, efficient, and sustainable transportation infrastructure.
- Neglecting any of these factors can result in poor road performance, increased maintenance costs, and potential safety hazards.
- Hence, a comprehensive approach that takes into account all these factors is necessary for proper road alignment.