## **Core Concept**
The question assesses knowledge of typical language development milestones in children, specifically focusing on the age at which a child can use 10 words with meaning. Language development is a crucial aspect of pediatric assessment, reflecting cognitive and social development.

## **Why the Correct Answer is Right**
By 18 months, most children have a vocabulary of around 5-20 words and start combining two words together. The ability to use 10 words with meaning is a milestone typically achieved around this age, marking an important step in language acquisition. This skill is part of the Denver Developmental Screening Test and other assessments used to monitor child development.

## **Why Each Wrong Option is Incorrect**
* **Option A:** 12 months - At this age, children usually have a vocabulary of 1-5 words and are just beginning to say their first words. Using 10 words with meaning is generally beyond their capability.
* **Option B:** 15 months - Children at this age may have around 5-10 words in their vocabulary but might not consistently use them with meaning or in context.
* **Option D:** 24 months - By 24 months, children typically have a vocabulary of 50 words or more and start forming simple sentences. While they certainly can use 10 words with meaning, this is slightly later than the typical age for achieving this specific milestone.

## **Clinical Pearl / High-Yield Fact**
A key point to remember is that language development can vary widely among children. However, by 18 months, most children should be able to say a few words to communicate and understand simple instructions. Significant delays in language development should prompt further evaluation for potential issues.

## **Correct Answer:** . 18 months.