The correct answer is option 'C' - Kyphosis.

Kyphosis is a deformity characterized by an exaggerated forward rounding of the upper back. It leads to a hunched or stooped posture and can cause various health issues if left untreated. In the case of Raju, the physical education teacher observed an increase or exaggeration of the posterior curve, which is indicative of kyphosis.

Explanation:

1. What is Kyphosis?
Kyphosis is a condition that affects the spine, causing an abnormal curvature in the upper back. The normal spine has natural curves that help with shock absorption and overall flexibility. However, when the curve in the upper back becomes excessively rounded, it is referred to as kyphosis.

2. Causes of Kyphosis:
- Poor posture: Slouching or sitting in a hunched position for extended periods can contribute to the development of kyphosis.
- Osteoporosis: Weakening of the bones due to osteoporosis can lead to compression fractures in the spine, resulting in kyphosis.
- Congenital or developmental factors: Some individuals may have a naturally more rounded upper back due to developmental issues or genetic factors.
- Scheuermann's disease: This condition typically affects adolescents and causes the vertebrae to grow unevenly, leading to kyphosis.
- Muscular dystrophy: Certain muscular conditions can weaken the muscles supporting the spine, causing it to curve forward.

3. Symptoms of Kyphosis:
- Rounded or hunched appearance of the upper back
- Back pain or stiffness
- Fatigue or muscle weakness
- Difficulty breathing or shortness of breath in severe cases

4. Treatment of Kyphosis:
- Physical therapy: Exercises and stretches can help improve posture, strengthen the back muscles, and alleviate pain.
- Bracing: In some cases, wearing a brace can help correct the curvature and prevent it from worsening, especially in growing children.
- Medication: Pain relievers or anti-inflammatory drugs may be prescribed to manage discomfort.
- Surgery: In severe cases or when other treatments have been ineffective, surgery may be required to correct the curvature.

In conclusion, kyphosis is a condition characterized by an exaggerated forward rounding of the upper back. It can be caused by various factors, and treatment options range from physical therapy to surgery, depending on the severity of the condition.