## **Core Concept**
The question tests knowledge of human dentition development, specifically the number of teeth present in a child's mouth at a certain age. By age 12, most children have a mix of primary (baby) teeth and permanent teeth. Understanding the typical sequence and timing of tooth eruption is essential.

## **Why the Correct Answer is Right**
By the age of 12, children typically have 28 permanent teeth, as the first molars (4 total, one in each quadrant), central incisors (4 total), lateral incisors (4 total), canines (4 total), and first premolars (4 total) have erupted, replacing most of the primary teeth. The second premolars and second molars usually erupt later. This makes the correct count.

## **Why Each Wrong Option is Incorrect**
- **Option A:** 20 teeth - This number is too low for a 12-year-old, as it might represent a count from an earlier age when fewer permanent teeth have erupted.
- **Option B:** 24 teeth - This is still short of the typical number; it might account for the incisors, canines, and first molars but misses the premolars.
- **Option D:** 32 teeth - This number represents a full adult dentition, which is not typical for a 12-year-old since the second molars (wisdom teeth) usually have not erupted yet.

## **Clinical Pearl / High-Yield Fact**
A key point to remember is that the sequence of tooth eruption can vary, but by age 12, most children should have a significant number of permanent teeth. This timeline is crucial for pediatric dentistry and orthodontic assessments.

## **Correct Answer:** . 28 teeth