## **Core Concept**
The color of a bruise can indicate its age due to the breakdown and absorption of blood products over time. This process involves the sequential action of various enzymes on hemoglobin, leading to the formation of different pigments.

## **Why the Correct Answer is Right**
The greenish color of a bruise typically appears during the healing process as the body breaks down hemoglobin into biliverdin, which is green in color. This usually occurs around 5-7 days after the injury. Therefore, a bruise that is greenish in color is approximately 5-7 days old.

## **Why Each Wrong Option is Incorrect**
- **Option A:** This option is incorrect because it does not specify a timeframe that matches the greenish coloration of a bruise.
- **Option B:** This option suggests a timeframe that might be too early for the greenish color to appear.
- **Option D:** This option suggests a timeframe that might be too late for the initial greenish coloration, as bruises typically progress through various colors (red, blue, purple, green, yellow, brown) before fading.

## **Clinical Pearl / High-Yield Fact**
A useful mnemonic to remember the color changes and approximate ages of bruises is:
- Red/Purple: 0-2 days
- Blue/Black: 2-5 days
- **Greenish:** 5-7 days
- Yellow/Brown: 7-14 days
- Normal skin color: 14+ days

## **Correct Answer:** C. 5-7 days.