**Core Concept**
Fluconazole and ketoconazole are both antifungal medications, but they belong to different classes of drugs and have distinct mechanisms of action. Fluconazole is an azole antifungal, which inhibits the enzyme lanosterol 14α-demethylase, whereas ketoconazole is also an azole antifungal but has a broader spectrum of activity and can inhibit other enzymes as well.

**Why the Correct Answer is Right**
Fluconazole is primarily used to treat fungal infections such as candidiasis, cryptococcosis, and histoplasmosis. Its mechanism of action involves the inhibition of lanosterol 14α-demethylase, which is a critical enzyme in the biosynthesis of ergosterol, an essential component of fungal cell membranes. In contrast, ketoconazole has a broader spectrum of activity and can inhibit other enzymes, including 17α-hydroxylase, which is involved in the biosynthesis of steroids. This broader spectrum of activity makes ketoconazole more effective against a wider range of fungal infections, but it also increases the risk of side effects.

**Why Each Wrong Option is Incorrect**
**Option A:** Incorrect because fluconazole and ketoconazole both have similar mechanisms of action and are both azole antifungals.
**Option B:** Incorrect because fluconazole and ketoconazole both have similar pharmacokinetic profiles and are both metabolized by the liver.
**Option C:** Incorrect because fluconazole and ketoconazole both have similar dosage forms and are both available as oral tablets or solutions.

**Clinical Pearl / High-Yield Fact**
It's essential to note that fluconazole and ketoconazole have different safety profiles and can cause different side effects. Ketoconazole is more likely to cause liver damage and should be used with caution in patients with pre-existing liver disease.

**Correct Answer:** D.