Concept:Oil palm trees require slightly acidic soil conditions for healthy growth.Explanation:The oil palm, Elaeis guineensis, performs best when the soil pH is between 5.5 and 6.5.This pH range is acidic to slightly acidic.Soils within this range allow proper nutrient uptake and root development.Therefore, the correct option is the one that states 5.5−6.5.Answer:C. 5.5−6.5