**Core Concept**
Bezold's abscess is a complication of a mastoiditis, which is an infection of the mastoid part of the temporal bone. The abscess forms when the infection breaks through the cortex of the mastoid bone. Understanding the anatomical relationships of the mastoid bone is crucial for identifying the location of Bezold's abscess.

**Why the Correct Answer is Right**
The correct answer is related to the anatomical location of Bezold's abscess. Bezold's abscess is typically located deep to the sternocleidomastoid muscle. This muscle is a key landmark in the neck, and its relationship to the mastoid bone is important for understanding the potential pathways of infection spread.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because the abscess is not typically located deep to this structure.
**Option B:** Similarly, this option is incorrect as it does not accurately describe the location of Bezold's abscess.
**Option C:** This option is also incorrect as the relationship between the abscess and this structure is not anatomically consistent.

**Why Each Wrong Option is Incorrect (Continued)**
**Option D:** This is the correct location, but since we are looking for why the other options are wrong, we focus on their inaccuracy.

**Clinical Pearl / High-Yield Fact**
Bezold's abscess is a significant complication because it can lead to further spread of infection into the neck, potentially involving vital structures. Recognizing the signs and symptoms of mastoiditis and its complications is crucial for prompt treatment.

**Correct Answer:** Correct Answer: D. sternocleidomastoid muscle.