**Core Concept**
Acute rheumatic fever (ARF) is a complication of untreated or inadequately treated group A beta-hemolytic streptococcal (GABHS) pharyngitis. The disease is characterized by an autoimmune response triggered by molecular mimicry between the streptococcal antigens and host tissues.

**Why the Correct Answer is Right**
The mechanism of acute rheumatic fever is thought to involve the activation of autoreactive T cells and B cells, which cross-react with host tissues. This is facilitated by the presence of shared epitopes between the streptococcal M protein and human cardiac myosin. The immune response leads to the production of antibodies against these cross-reactive epitopes, resulting in inflammation and damage to the heart, joints, and other tissues. The most commonly affected heart structures are the mitral and aortic valves, which become thickened and inflamed due to the autoimmune response.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect as it does not accurately describe the autoimmune mechanism of acute rheumatic fever.
**Option B:** This option is incorrect as it suggests a direct bacterial invasion of the heart, which is not the primary mechanism of acute rheumatic fever.
**Option C:** This option is incorrect as it implies a viral etiology for acute rheumatic fever, which is not supported by evidence.

**Clinical Pearl / High-Yield Fact**
The Jones criteria, developed in 1944, are a set of clinical and laboratory criteria used to diagnose acute rheumatic fever. The major criteria include carditis, arthritis, chorea, subcutaneous nodules, and erythema marginatum, while the minor criteria include fever, arthralgia, and laboratory evidence of inflammation.

**Correct Answer: D**