## Core Concept
Language development in children follows a relatively predictable pattern. The age at which a child starts speaking sentences of a few words is an important milestone in assessing their linguistic and cognitive development. Typically, children start combining words into short sentences around a specific age range.

## Why the Correct Answer is Right
The correct answer, **18 months**, is a reasonable estimate for when many children begin to say sentences with a few words. Language development varies among children, but generally, by 18 months, children often have a vocabulary of around 20 words and start putting two words together. By 24 months, most children are saying around 50 words and combining two words together in short sentences. Therefore, saying sentences of a few words around 18 months aligns with typical language development milestones.

## Why Each Wrong Option is Incorrect
- **Option A: 6 months**: At 6 months, infants are beginning to babble and make cooing sounds, but they are not yet forming sentences with words. This is too early for sentence formation.
- **Option B: 12 months**: Around 12 months, children usually say a few words, like "mama" or "dada," but they are not yet combining words into short sentences. This is still early for forming sentences.
- **Option D: 3 years**: By 3 years, children's language skills have significantly advanced, and they are typically forming short sentences and having simple conversations. This is later than when they first start forming sentences of a few words.

## Clinical Pearl / High-Yield Fact
A key point to remember is that there is a wide range of normal for language development. However, by 24 months, most children should be saying around 50 words and combining two words together. If a child is not saying any words by 16 months or not combining two words together by 24 months, it may indicate a language delay, and further evaluation is warranted.

**Correct Answer: C. 18 months.**