I think there might be some confusion - the question is actually about acne, not anaesthesia. Here's the explanation for the given question:

**Core Concept**
Acne is a complex skin condition that involves the interplay of multiple factors, including hormonal influences, bacterial colonization, and keratinization abnormalities.

**Why the Correct Answer is Right**
The causative factors of acne include androgens, which stimulate sebum production and contribute to comedone formation. Bacterial contamination, particularly by Propionibacterium acnes (P. acnes), plays a significant role in the development of acne by contributing to inflammation and comedone formation. Hypercornification of the duct, leading to the formation of comedones, is another key factor in the pathogenesis of acne. However, food is not a direct causative factor for acne, although certain dietary factors may exacerbate the condition.

**Why Each Wrong Option is Incorrect**
**Option A:** Androgen is a correct causative factor for acne, as it stimulates sebum production and contributes to comedone formation.
**Option C:** Bacterial contamination is also a correct causative factor for acne, as it contributes to inflammation and comedone formation.
**Option D:** Hypercornification of the duct is a correct causative factor for acne, as it leads to the formation of comedones.

**Clinical Pearl / High-Yield Fact**
It's essential to note that while food is not a direct causative factor for acne, certain dietary factors such as dairy products, refined carbohydrates, and processed foods may exacerbate the condition. A balanced diet and good skincare habits can help manage acne.

**Correct Answer Line**
✓ Correct Answer: B. Only food