**Core Concept**
The question requires understanding of the relationship between spinal cord injuries and their corresponding neurological deficits. The **spinal cord** is organized into segments, each corresponding to specific dermatomes and myotomes, which are areas of skin and muscle innervated by nerves arising from specific spinal nerve roots.

**Why the Correct Answer is Right**
Given the patient's symptoms, including quadriparesis (weakness in all four limbs), sphincter disturbance, and a sensory level up to the upper border of the sternum, the lesion is likely at a high cervical level. The **cervical spine** is responsible for controlling arm and leg function, as well as certain automatic functions like breathing. A lesion at this level would explain the patient's respiratory distress, as indicated by a respiratory rate of 35/minute, due to impairment of the **diaphragm** and accessory respiratory muscles.

**Why Each Wrong Option is Incorrect**
**Option A:** Injuries at this level would not typically result in quadriparesis or the specific sensory level described.
**Option B:** This level of injury would likely result in more localized deficits.
**Option D:** This would result in paraplegia rather than quadriparesis.

**Clinical Pearl / High-Yield Fact**
A key point to remember is that the level of the sensory deficit can help localize the lesion in spinal cord injuries. Injuries above C5 can lead to respiratory failure due to loss of diaphragmatic function.

**Correct Answer:** C. C5