Concept:Mental retardation (intellectual disability) is classified by IQ range. Moderate retardation (IQ 35-50) is categorized as trainable.Explanation:Children with moderate mental retardation can learn functional academics and self‑help skills. They typically reach the intellectual level of a non‑retarded 7‑or‑8‑year‑old. With training, they can work in unskilled or semi‑skilled jobs under supervision. They learn to talk and communicate during preschool but cannot live independently and need care from family or institutions. About 10% of mentally retarded persons fall into this group. They adapt well to supervised community living. Thus, moderate mentally retarded are called trainable mentally retarded.Educable mentally retarded (IQ 50‑70) can learn basic academic subjects. Custodial mentally retarded (severe/profound) require constant care in a residential setting. Readable is not a recognized category.Answer:A. Trainable mentally retarded