**Core Concept**
The volume of distribution (Vd) of a drug is a pharmacokinetic parameter that represents the ratio of the total amount of a drug in the body to its concentration in the plasma. It is a measure of how a drug distributes between plasma and the rest of the body tissues.

**Why the Correct Answer is Right**
The correct formula for calculating the volume of distribution is Vd = (Dose/Conc), where Dose is the amount of drug administered and Conc is the plasma concentration of the drug at steady state. This formula is derived from the concept that the volume of distribution represents the volume of body fluid that would contain the same amount of drug as is present in the plasma. By rearranging the formula for the steady-state concentration, we can solve for Vd.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because it does not accurately represent the formula for calculating the volume of distribution.
**Option B:** This option is incorrect because it is a formula for calculating the clearance of a drug, not its volume of distribution.
**Option C:** This option is incorrect because it is a formula for calculating the half-life of a drug, not its volume of distribution.

**Clinical Pearl / High-Yield Fact**
The volume of distribution is an important pharmacokinetic parameter that helps predict how a drug will behave in the body. A high volume of distribution indicates that the drug is highly lipophilic and will distribute extensively into body tissues, whereas a low volume of distribution indicates that the drug is highly hydrophilic and will remain mainly in the plasma.

**Correct Answer:** . Vd = (Dose/Conc)