## Core Concept
The development of language skills, particularly the use of verb tenses such as past and present, is an important milestone in a child's cognitive and linguistic development. This skill is closely related to the child's ability to understand and express time concepts.

## Why the Correct Answer is Right
Children typically begin to use past and present tense correctly around the age of 2-3 years. This is part of their language development where they start to grasp and express temporal concepts through verb tense changes. For example, they might say "I go" (present tense) and "I went" (past tense). This ability reflects improvements in their understanding of grammar and their capacity for more complex communication.

## Why Each Wrong Option is Incorrect
* **Option A:** This option is incorrect because it does not accurately represent the age range associated with the development of using past and present tense.
* **Option B:** This option is incorrect because it suggests an age that is either too early or too late for the specific linguistic milestone of using past and present tense.
* **Option D:** This option is incorrect because it also does not accurately represent the age range for this linguistic development.

## Clinical Pearl / High-Yield Fact
A key point to remember is that by around 2-3 years of age, children often exhibit an understanding of basic time concepts through their use of language, such as correctly applying past and present tense. Language development can vary among children, but significant delays or difficulties may warrant further evaluation.

**Correct Answer: C. 2-3 years.**