The location of the iron and steel industry at Ajaokuta in Nigeria can be best explained by considering certain factors critical to the iron and steel production process. These factors include **availability of raw materials**, **efficient transportation networks**, and **proximity to fuel sources**.
Firstly, the presence of **iron ore at Itakpe** is crucial because iron ore is the primary raw material needed for steel production. The proximity of Itakpe's iron ore deposits to Ajaokuta reduces transportation costs and ensures a steady supply of the primary raw material, enhancing the industry's efficiency. Therefore, **availability of iron ore is a significant consideration**.
Secondly, **limestone at Ewekoro** is essential because limestone is a critical component used in removing impurities during the steelmaking process, particularly in the blast furnace. Limestone acts as a flux which combines with impurities and forms slag that can be easily removed. **Proximity to limestone sources ensures access to necessary materials for processing**, which is a factor in choosing the location of the industry.
The presence of a **river port at Lokoja** facilitates the transportation of raw materials and finished products, as waterways provide a cost-effective and efficient means of transportation. This is important for both importing required materials and exporting the finished steel products.
Additionally, **coal at Orukpa and Okaba** is important as coal is often used to generate the high temperatures needed in steel production, either directly or through the production of coke, a coal derivative used in blast furnaces.
In conclusion, the location of the iron and steel industry at Ajaokuta is best explained by the presence of:
- Iron ore at Itakpe, for the primary raw material.
- Limestone at Ewekoro, for aiding the processing in steelmaking.
Therefore, the most relevant factors are the **availability of iron ore and limestone**, making the best answer "I and II only".