**Core Concept**
The question is testing the student's knowledge of local anaesthetics, specifically their use as surface anaesthetics. Surface anaesthetics are used to numb the skin or mucous membranes before minor surgical procedures.

**Why the Correct Answer is Right**
Bupivacaine is a long-acting local anaesthetic commonly used for regional anaesthesia, infiltration anaesthesia, and epidural anaesthesia. It is not typically used as a surface anaesthetic due to its high potency and potential for toxicity when applied topically. In contrast, other local anaesthetics like lidocaine, benzocaine, and tetracaine are commonly used as surface anaesthetics.

**Why Each Wrong Option is Incorrect**
**Option A:** Lidocaine is a commonly used surface anaesthetic, making it incorrect for this question. It is often applied topically to numb the skin or mucous membranes before minor procedures.
**Option B:** Benzocaine is another surface anaesthetic, often used in ointments or sprays for minor procedures. It is incorrect as a choice for this question.
**Option D:** Tetracaine is a long-acting local anaesthetic that can be used as a surface anaesthetic, making it incorrect for this question.

**Clinical Pearl / High-Yield Fact**
When using local anaesthetics, it's essential to consider their potency, duration of action, and potential for toxicity. Surface anaesthetics should be used in a controlled manner to minimize the risk of systemic toxicity.

**Correct Answer:** C. Bupivacaine. Bupivacaine is not used as a surface anaesthetic due to its high potency and potential for toxicity when applied topically.