## Core Concept
Ludwig's angina is a severe infection of the neck and floor of the mouth, characterized by rapidly spreading cellulitis. It involves multiple spaces, including the sublingual and submandibular spaces, and can lead to significant airway compromise. The condition requires prompt recognition and management to prevent serious complications.

## Why the Correct Answer is Right
The correct answer encompasses several key features of Ludwig's angina:
- **Rapidly spreading cellulitis of the neck (a)**: This is a hallmark of Ludwig's angina, which can quickly progress and compromise the airway.
- **Edema of the floor of the mouth (c)**: This is a critical aspect, as the swelling can elevate the tongue and cause airway obstruction.
- **Sub-lingual and sub-maxillary spaces are involved (d)**: Ludwig's angina characteristically involves these spaces, leading to the clinical presentation.
- **When operated, ↓GA chances of aspiration, shock can develop (e)**: Management often involves securing the airway, and surgical intervention may be required. However, general anesthesia (GA) can increase the risk of aspiration, and the patient is at risk of developing shock.

## Why Each Wrong Option is Incorrect
- **Option B: H. Influenzae is most common organism**: While *H. influenzae* can cause infections in the head and neck, Ludwig's angina is most commonly associated with infections originating from dental sources, such as *Streptococcus viridans*, *Staphylococcus aureus*, and anaerobic bacteria. *H. influenzae* type b was a common cause before widespread vaccination.

## Clinical Pearl / High-Yield Fact
A critical clinical pearl is that Ludwig's angina can lead to life-threatening airway obstruction. Early recognition and airway management are crucial. The infection often originates from dental infections, highlighting the importance of dental health in preventing such conditions.

## Correct Answer: D.