**Core Concept**
Duchenne Muscular Dystrophy (DMD) is a genetic disorder caused by the deficiency of dystrophin, a critical protein for muscle function and integrity. This protein is encoded by the dystrophin gene, located on the X chromosome. The disease primarily affects males due to the X-linked recessive inheritance pattern.

**Why the Correct Answer is Right**
The absence or mutation of the dystrophin gene leads to the production of a dysfunctional protein, which disrupts the dystrophin-glycoprotein complex (DGC). This complex is essential for maintaining muscle cell membrane stability and integrity. As a result, muscle cells become more susceptible to damage from mechanical stress, leading to progressive muscle degeneration and weakness.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because Duchenne Muscular Dystrophy is not primarily associated with mitochondrial dysfunction, although some mitochondrial myopathies may present with similar symptoms.

**Option B:** This option is incorrect because Becker Muscular Dystrophy is a milder form of DMD, also caused by dystrophin gene mutations, but it typically presents later in life and with slower disease progression.

**Option C:** This option is incorrect because Myotonic Dystrophy is a different genetic disorder characterized by muscle stiffness (myotonia) and wasting, caused by mutations in the dystrophia myotonica protein kinase (DMPK) gene.

**Clinical Pearl / High-Yield Fact**
Duchenne Muscular Dystrophy is often diagnosed between 2-5 years of age, with the first symptoms typically being delayed motor milestones, gait disturbances, and muscle weakness. Early recognition and management can significantly improve quality of life and prolong survival.

**Correct Answer:** D.