**Core Concept**
A bruise, also known as a contusion, is a type of injury characterized by the leakage of blood from damaged blood vessels into the surrounding tissues, resulting in discoloration and swelling. This occurs due to the extravasation of blood from the damaged vessels into the interstitial space.

**Why the Correct Answer is Right**
The correct answer choice **d) Extravasation of blood occurs** correctly describes the underlying pathophysiology of a bruise. When a blunt object strikes the skin, it causes damage to the blood vessels, leading to the leakage of blood into the surrounding tissues. This extravasation of blood is responsible for the characteristic discoloration and swelling associated with a bruise. The affected area becomes swollen, painful, and discolored due to the accumulation of blood in the interstitial space.

**Why Each Wrong Option is Incorrect**
**Option A:** A bruise is typically darker at the center, not at the point of contact/pressure. The point of contact may be lighter due to the compression of blood vessels.

**Option B:** While blood is indeed present in the vessel, it can be easily washed away, as the blood in a bruise is extravasated into the interstitial space, not contained within the blood vessels.

**Option C:** Bruises are typically seen at the site of injury, but the surrounding area may also be affected due to the spread of blood into the interstitial space.

**Clinical Pearl / High-Yield Fact**
It's essential to note that bruises can be classified into two types: **ecchymosis** (subcutaneous hemorrhage) and **hematoma** (collection of blood in a confined space). Understanding the difference between these two conditions is crucial for accurate diagnosis and management.

**Correct Answer:** d. Extravasation of blood occurs