**Core Concept**
Muscular dystrophies are a group of inherited disorders characterized by progressive muscle weakness and degeneration, often due to abnormalities in proteins that play a crucial role in maintaining muscle integrity.

**Why the Correct Answer is Right**
The presence of subsarcolemmal aggregates of rod-shaped intracytoplasmic inclusions in the muscle biopsy, along with normal serum creatine kinase levels, points towards a diagnosis of nemaline myopathy. Nemaline myopathy is a congenital muscular dystrophy characterized by the presence of nemaline rods, which are abnormal aggregates of actin filaments. The disease typically presents with weakness and hypotonia in infancy or early childhood, with some patients having a relatively mild course and maintaining the ability to ambulate unassisted.

**Why Each Wrong Option is Incorrect**
**Option A:**
Duchenne muscular dystrophy is characterized by progressive weakness and degeneration of skeletal muscles, often presenting with elevated serum creatine kinase levels, which is not the case in this patient.

**Option B:**
Becker muscular dystrophy is a milder form of Duchenne muscular dystrophy, also characterized by elevated serum creatine kinase levels, which is not present in this patient.

**Option C:**
Myotonic dystrophy is characterized by myotonia, muscle pain, and wasting, which are not present in this patient.

**Clinical Pearl / High-Yield Fact**
Nemaline myopathy is the most common form of congenital muscular dystrophy, and it can be inherited in an autosomal dominant or recessive pattern.

**Correct Answer:** C.