Okay, let's tackle this question. The scenario describes a 5-year-old boy with normal motor skills but severe language delay. He doesn't interact with others and is into spinning. The key here is to figure out the most likely diagnosis.

First, I need to recall the differential diagnoses for developmental delays, especially in young children. The main possibilities here are autism spectrum disorder (ASD), intellectual disability, hearing impairment, and maybe other neurological conditions. But the question mentions normal motor skills, which might point away from some physical disabilities.

The severe language delay is a big clue. In ASD, communication deficits are a core feature. Also, the lack of interest in social interactions and repetitive behaviors like spinning are classic signs of autism. The age of onset is around this time too.

Hearing impairment could be considered, but if the motor skills are normal, that might not be the case. Intellectual disability might present with more generalized delays, not just language and social interaction. Down syndrome is an example, but again, motor skills might be affected there.

Looking at the options, if the correct answer is autism, then the other options would be incorrect. Let me check the distractors. Option A could be something like Down syndrome, B maybe hearing loss, C intellectual disability, D attention deficit hyperactivity disorder (ADHD).

Why is autism the right answer? Because the social interaction deficits, communication issues, and repetitive behaviors align with ASD. The spinning is a stereotypic behavior. Normal motor skills rule out some other conditions.

Now, why the other options are wrong: Down syndrome would have characteristic facial features and motor delays. Hearing loss would affect speech development but not necessarily the social interaction part. Intellectual disability is a broader term, but the specific behaviors point to autism. ADHD is more about hyperactivity and inattention, not the social and language aspects.

Clinical pearl: Remember that ASD is diagnosed based on social communication deficits and restricted, repetitive behaviors. Early signs include lack of eye contact, delayed speech, and not engaging in imaginative play. The spinning is a red flag for repetitive behaviors.

So the correct answer should be the one corresponding to autism spectrum disorder.

**Core Concept**
This question assesses the differential diagnosis of developmental disorders in children, focusing on **autism spectrum disorder (ASD)**. Key features include **impaired social interaction**, **communication deficits**, and **repetitive behaviors** (e.g., spinning), with normal motor development.

**Why the Correct Answer is Right**
Autism spectrum disorder is characterized by **persistent deficits in social communication/social interaction** (e.g., avoiding eye contact, lack of peer interest) and **restricted, repetitive patterns of behavior** (e.g., spinning, insistence on sameness). The child’s **severe language delay**, **lack of social engagement**, and **stereotypic spinning** align with DSM-5 criteria for ASD. Normal motor skills further support ASD over conditions like cerebral palsy or Down syndrome.

**Why Each Wrong Option is Incorrect**
**Option A:** *Down syndrome* presents with **distinct facial features**, **intellectual disability**, and **motor delays**, which are not mentioned here.
**Option B:** *Hearing impairment* would cause **delayed speech** but not necessarily **social withdrawal** or **repetitive behaviors**.
**Option C:** *Intellectual disability* involves **global cognitive deficits

✓ Correct Answer: D. Infantile autism