## **Core Concept**
Language development milestones are crucial in assessing a child's cognitive and communication skills. The ability to form sentences is a significant milestone that reflects the integration of vocabulary and grammatical skills.

## **Why the Correct Answer is Right**
At 24 months (2 years), a child's language skills typically advance to combining two words together, and by 30 months, they often start forming short sentences. By 36 months (3 years), most children can say sentences of six words or more, demonstrating an understanding of basic grammar and syntax. This developmental milestone aligns with the correct answer.

## **Why Each Wrong Option is Incorrect**
- **Option A:** Typically, at 24 months, children are just beginning to combine two words together, not forming sentences of six words.
- **Option B:** At 30 months, children's language skills are advancing, but they might only be forming short sentences of 3-4 words.
- **Option D:** By 48 months (4 years), children usually have more complex sentences, but saying a sentence of six words is generally achieved before this age.

## **Clinical Pearl / High-Yield Fact**
A useful mnemonic for language milestones is to remember that by 2 years, children say around 50 words and start combining two words. By 3 years, they use sentences of 5-6 words. Significant delays in these milestones may indicate a need for further evaluation.

## **Correct Answer:** C. 36 months.