Which of the following correctly depicts the dental formula of a child?

Options

A. `(2112)/(2112)`
B. `(2102)/(2102)`
C. `(2123)/(2123)`
D. `(2111)/(2111)`

Explanation

To determine the correct dental formula for a child, we need to understand the composition of a child's teeth, also known as deciduous or milk teeth. Here’s a step-by-step solution:

### Step 1: Understand the Types of Teeth
Children have four different types of teeth:
- **Incisors**: Used for cutting and biting.
- **Canines**: Pointed teeth used for tearing.
- **Premolars**: Used for crushing and grinding (not present in children).
- **Molars**: Used for grinding food.

### Step 2: Know the Total Number of Deciduous Teeth
A child typically has a total of **20 deciduous teeth**.

### Step 3: Determine the Arrangement of Teeth
The dental formula represents the number of each type of tooth in one half of the mouth (upper and lower jaws). For children, the dental formula is:
- Upper Jaw: 2 Incisors, 1 Canine, 0 Premolars, 2 Molars
- Lower Jaw: 2 Incisors, 1 Canine, 0 Premolars, 2 Molars

### Step 4: Write the Dental Formula
The dental formula for a child can thus be expressed as:
\[ \text{Dental Formula} = \frac{2 \, 1 \, 0 \, 2}{2 \, 1 \, 0 \, 2} \]
This can be simplified to:
\[ 2 \, 1 \, 0 \, 2 \, \text{by} \, 2 \, 1 \, 0 \, 2 \]
This means:
- 2 Incisors
- 1 Canine
- 0 Premolars
- 2 Molars

### Step 5: Choose the Correct Option
From the options provided:
1. 2112 by 2112
2. **2102 by 2102** (This is the correct answer)
3. 2123 by 234
4. 1111 by 1111

The correct dental formula for a child is **2102 by 2102**.

### Final Answer
The correct answer is **2102 by 2102**.

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