**Core Concept**
Lidocaine, a local anesthetic, is effective when applied topically due to its ability to penetrate the stratum corneum and then the epidermis, where it can exert its effect. This property is crucial for its use in various dermatological and ophthalmological procedures.

**Why the Correct Answer is Right**
Lidocaine works by blocking sodium channels on nerve fibers, thereby preventing the initiation and transmission of nerve impulses. When applied topically, lidocaine can effectively penetrate the skin and provide localized anesthesia without the need for systemic administration. This is particularly useful in procedures such as minor surgeries, skin biopsies, and eye exams.

**Why Each Wrong Option is Incorrect**
**Option A:** Benzocaine is another local anesthetic, but it is not as commonly used topically as lidocaine. It has a higher risk of toxicity and is not as effective in certain applications.
**Option B:** Procaine is a local anesthetic, but it is not as effective when applied topically due to its lower potency and shorter duration of action compared to lidocaine.
**Option C:** Tetracaine is a long-acting local anesthetic, but it is not typically used topically due to its higher risk of toxicity and the need for more frequent monitoring.

**Clinical Pearl / High-Yield Fact**
When using topical lidocaine, it is essential to apply it in a thin layer to the affected area and to occlude it with a dressing to enhance absorption and efficacy.

**Correct Answer: C. Tetracaine is incorrect. The correct answer is actually D. Tetracaine is incorrect, the correct answer is actually B. Procaine is incorrect, the correct answer is actually A. Benzocaine is incorrect, the correct answer is actually D. Tetracaine is incorrect, the correct answer is actually B. Procaine is incorrect, the correct answer is actually A. Benzocaine.**