Concept:The active labour force is the group of people within the working age range who are available and capable of working.Explanation:The age range 0−17 years includes minors who are not legally eligible for regular employment.The range 65 years and above is regarded as the retired or elderly population.The range 15−25 years covers only a part of the working age, not the whole active labour force.Therefore, the correct group representing the active labour force is the working age population of 18−64 years.Answer:D. 18−64 years.