Final answer:
A 3-year-old should have 16 teeth visible in their mouth, which are their baby teeth or deciduous teeth.
Step-by-step explanation:
The correct answer is a) 16 teeth. By the age of three, a toddler should have all of their 20 deciduous teeth, also known as baby teeth, fully emerged. These baby teeth include eight incisors, four cuspids or canines, and eight molars. The remaining permanent teeth, which include premolars and additional molars, generally start to replace the baby teeth between the ages of six and 12.