**Question:** Handedness develops by age of

A. Birth
B. 6 months
C. 2 years
D. 3 years

**Core Concept:**
Handedness, also known as handedness or lateralization of function, refers to the preference for using one hand over the other for various activities, such as writing or grasping objects. In humans, handedness develops during early childhood, and the process is influenced by genetic and environmental factors.

**Why the Correct Answer is Right:**
The correct answer is **D. 3 years**. Handedness typically emerges around the age of 3 years, when children begin to demonstrate a consistent preference for using one hand over the other. This is due to the maturation of the cerebral cortex, particularly the language and motor areas, and the development of neural connections that allow for the efficient execution of tasks with one hand.

**Why Each Wrong Option is Incorrect:**
A) Birth: Although some infants may show preferences early on, handedness develops later as the brain matures and the neural connections mature.
B) 6 months: This is too early, as handedness typically emerges around 3 years and becomes more pronounced during adolescence.
C) 2 years: Similar to option B, handedness develops later in childhood, not during the toddler stage.

**Why the Correct Answer is Right:**
By around 3 years of age, the brain regions responsible for language and motor control, such as the primary motor cortex and Broca's area, have undergone significant development. This allows for the emergence of handedness as children start demonstrating a consistent preference for using one hand over the other during activities like grasping objects or writing.

**Why Each Wrong Option is Incorrect:**
A) Birth: Handedness develops later in childhood due to brain maturation and neural connections.
B) 6 months: Handedness emerges around 3 years, not during the infant stage.
C) 2 years: Handedness develops later in childhood, not during the toddler stage.

**Clinical Pearl:**
Recognizing the development of handedness around the age of 3 years can be useful for healthcare professionals when assessing children's motor skills and cognitive abilities. Understanding the typical age at which handedness emerges can help differentiate between typical development and potential developmental delays or neurological issues.

**Why Each Wrong Option is Incorrect:**
A) Birth: Handedness develops later in childhood due to brain maturation and neural connections.
B) 6 months: Handedness emerges around 3 years, not during the infant stage.
C) 2 years: Handedness develops later in childhood, not during the toddler stage.