**Core Concept:** Quinsy is a severe condition characterized by an abscess in the pharynx, particularly in the tonsillar area. Treatment often involves antibiotics and, in some cases, a tonsillectomy.

**Why the Correct Answer is Right:** Quinsy is an acute tonsillitis complicated by a retropharyngeal abscess, which is a collection of pus in the area between the tonsils and the back of the tongue. The correct answer, option D, refers to the immediate tonsillectomy being a part of the treatment plan for quinsy. In severe cases, tonsillectomy is required to relieve the pressure and drainage of the abscess. Penicillin is often used as the initial antibiotic therapy due to its efficacy against common causative organisms like Streptococcus pyogenes.

**Why Each Wrong Option is Incorrect:**

A. Penicillin is not the only antibiotic used in quinsy treatment. Other antibiotics like clindamycin or doxycycline can also be prescribed, depending on the causative organisms and patient factors.
B. The abscess's location is in the tonsillar area, not the capsule. Quinsy occurs due to an abscess in the retropharyngeal space, not within the tonsillar capsule itself.
C. Quinsy can occur bilaterally in some cases, but it is not a universal feature. The question does not mention bilateral involvement, so stating it as a common feature is incorrect.
D. In addition to immediate tonsillectomy, other treatment modalities are also required, such as antibiotics, pain management, and supportive care. Quinsy treatment has a multi-faceted approach, and option D focuses on one part of it.

**Clinical Pearl:**

Quinsy is a severe complication of tonsillitis and requires prompt medical attention. The correct treatment plan comprises antibiotics, tonsillectomy (if necessary), pain management, and supportive care. The treatment aims to relieve the pressure and reduce the risk of respiratory compromise, sepsis, and airway obstruction. Understanding the correct treatment approach is essential for managing patients with quinsy effectively.