## Core Concept
The process of wound healing involves several stages, including inflammation, proliferation, and remodeling. During the remodeling phase, the collagen fibers are reorganized, and the tensile strength of the wound increases.

## Why the Correct Answer is Right
The tensile strength of a wound is primarily gained during the remodeling phase, which can last for months to years. By around 3-4 weeks (or approximately 21-28 days) post-injury, the wound has gained a significant portion of its tensile strength. Studies have shown that by this time, nearly 20% of the normal tensile strength of the tissue at the site of the wound is regained. This is due to the continued deposition and remodeling of collagen.

## Why Each Wrong Option is Incorrect
* **Option A:** This option is incorrect because it does not accurately reflect the timeframe for gaining 20% of the normal tensile strength.
* **Option B:** This option suggests a timeframe that is too short for significant tensile strength gain.
* **Option D:** This option suggests a timeframe that is longer than necessary for achieving 20% tensile strength.

## Clinical Pearl / High-Yield Fact
A key point to remember is that the tensile strength of a wound continues to increase over time, but it may take up to a year or more for a wound to regain 70-80% of its original tensile strength. The rate of strength gain is not linear and slows down over time.

## Correct Answer: C. 3 weeks.