## Core Concept
The question tests the understanding of local anesthetic dosing, specifically lignocaine (lidocaine) with adrenaline (epinephrine), which is crucial in clinical practice to prevent toxicity. Lignocaine is a commonly used local anesthetic, and the addition of adrenaline helps in prolonging its action and reducing systemic absorption.

## Why the Correct Answer is Right
The maximum recommended dose of lignocaine when used with adrenaline is **7 mg/kg**. Adrenaline causes vasoconstriction, which decreases the rate of absorption of lignocaine into the bloodstream, thereby reducing the risk of systemic toxicity and allowing for a higher dose. This is a critical consideration in procedures requiring local anesthesia.

## Why Each Wrong Option is Incorrect
* **Option A (2 mg/kg):** This dose is too low and is actually more reflective of the maximum dose of lignocaine without adrenaline, which is about 4-5 mg/kg.
* **Option B (4 mg/kg):** This is closer to the dose of lignocaine without adrenaline and is still below the maximum safe dose when adrenaline is used.
* **Option D (10 mg/kg):** This exceeds the recommended maximum dose even with adrenaline and would significantly increase the risk of systemic toxicity.

## Clinical Pearl / High-Yield Fact
A key point to remember is that the addition of adrenaline to local anesthetics like lignocaine allows for a higher maximum dose due to reduced systemic absorption. This is particularly important in procedures where larger volumes of anesthetic are required.

## Correct Answer: C. 7 mg/kg.