**Core Concept:** Pustular psoriasis is a subtype of psoriasis characterized by the formation of sterile pustules on the skin, typically on the palms and soles. The treatment focuses on reducing inflammation, alleviating symptoms, and preventing complications.

**Why the Correct Answer is Right:**
The correct answer (C) is based on the understanding of the pathophysiology and management of pustular psoriasis. Pustular psoriasis is a type of psoriasis that involves an immune response and inflammation, particularly in the dermal papillae. The treatment options aim to suppress the immune system, reduce inflammation, and prevent infection. Systemic corticosteroids (e.g., prednisolone) are prescribed to target these aspects.

**Why Each Wrong Option is Incorrect:**
A. Topical corticosteroids (e.g., clobetasol) are not as effective due to limited penetration into the dermal papillae where the inflammation occurs.
B. Phototherapy (e.g., UVB) primarily targets the epidermis and is less effective for the deeper dermal inflammation seen in pustular psoriasis.
D. Methotrexate is an immunosuppressive agent, but due to its systemic nature, it may cause more severe side effects.

**Clinical Pearl:**
Pustular psoriasis is a distinct subtype of psoriasis that requires systemic treatment with corticosteroids like prednisolone to penetrate the dermal papillae and suppress the inflammatory response. Inadequate treatment can lead to complications like pustule rupture and secondary infections.

**Correct Answer:** C. Systemic corticosteroids (e.g., prednisolone) are preferred for pustular psoriasis treatment due to their ability to penetrate the dermal papillae and suppress inflammation systemically.