**Core Concept**
The development of permanent teeth in children involves a complex process of tooth eruption and replacement of primary teeth. The primary and permanent dentition have distinct characteristics, and understanding the timing of tooth eruption is essential for pediatric dental care.

**Why the Correct Answer is Right**
By the age of 8, most children have a mix of primary and permanent teeth. The permanent teeth start erupting when the child is around 6 years old, and this process continues until they are about 12 years old. The first permanent teeth to erupt are typically the first molars and lower central incisors. By the age of 8, most children have 8 permanent teeth, including 4 incisors and 4 molars.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect as it is too high; most children do not have more than 8 permanent teeth by the age of 8.
**Option B:** This option is incorrect as it is too low; children typically have more than 4 permanent teeth by the age of 8.
**Option C:** This option is incorrect as it does not accurately reflect the number of permanent teeth present in an 8-year-old child.
**Option D:** This option is incorrect as it is too high; most children do not have more than 10 permanent teeth by the age of 8.

**Clinical Pearl / High-Yield Fact**
The timing of tooth eruption can vary significantly among children, and some may have all their primary teeth replaced by permanent teeth before the age of 8. It is essential for pediatricians and dentists to be aware of these variations and provide appropriate dental care.

**Correct Answer: B. 4**