**Core Concept**
Biotransformation refers to the metabolic conversion of drugs in the body, primarily in the liver, to facilitate elimination. It involves phase I and phase II reactions that typically increase hydrophilicity (polarity) to enhance excretion via urine or bile.

**Why the Correct Answer is Right**
Biotransformation converts less polar (more lipophilic) drugs into more polar (hydrophilic) metabolites. This process enhances solubility for excretion. Option B ("Polar to less polar") is incorrect because it contradicts the fundamental goal of biotransformation—increasing polarity, not decreasing it. The transformation generally moves from lipophilic to hydrophilic forms.

**Why Each Wrong Option is Incorrect**
Option A: Active metabolite generation is a well-documented phenomenon; e.g., warfarin’s active metabolite.
Option C: "Less polar to more polar" is correct and aligns with biotransformation—this is the standard pathway.
Option D: Prodrugs are converted to active forms via biotransformation (e.g., oseltamivir → oseltamivir carboxylate), making this true.

**Clinical Pearl / High-Yield Fact**
Remember: Biotransformation increases polarity to promote elimination. A key exam trap is confusing polarity changes—always think "less polar → more polar" as the rule, not the reverse.

✓ Correct Answer: B. Polar to less polar