## Core Concept
The rate of elimination of a drug refers to the rate at which the body removes the drug, typically expressed in terms of clearance (volume of plasma from which the drug is completely removed per unit time). This concept is crucial in pharmacokinetics as it helps in understanding how the concentration of a drug changes over time in the body.

## Why the Correct Answer is Right
The correct formula for the rate of elimination of a drug is given by the product of its clearance (Cl) and plasma concentration (Cp), i.e., Rate of elimination = Cl × Cp. This equation signifies that the rate at which a drug is eliminated from the body is directly proportional to its concentration in the plasma and the clearance, which reflects the efficiency of the elimination process.

## Why Each Wrong Option is Incorrect
- **Option A:** This option does not correctly represent the relationship between the rate of elimination, clearance, and plasma concentration.
- **Option B:** Similarly, this option does not accurately depict the formula for the rate of elimination of a drug.
- **Option D:** This option also fails to correctly represent the relationship between the rate of elimination and pharmacokinetic parameters like clearance and plasma concentration.

## Clinical Pearl / High-Yield Fact
A key point to remember is that clearance (Cl) is a critical pharmacokinetic parameter that can be used to predict the rate of elimination of drugs. Drugs with high clearance values are eliminated rapidly from the body, whereas drugs with low clearance values are eliminated more slowly. This concept is essential for understanding drug accumulation, potential toxicity, and the design of dosing regimens.

## Correct Answer: C. Cl × Cp