**Core Concept**
Competitive inhibition is a type of enzyme inhibition where an inhibitor binds to the active site of an enzyme, thereby blocking the substrate from binding and reducing the enzyme's activity. This type of inhibition is reversible and can be overcome by increasing the concentration of the substrate.

**Why the Correct Answer is Right**
Competitive inhibition is characterized by a decrease in the enzyme's affinity for the substrate, but an increase in the maximum velocity (Vmax) of the reaction. This is because the inhibitor competes with the substrate for binding to the active site, but does not affect the enzyme's catalytic activity once it is bound to the substrate. The enzyme-substrate complex still follows Michaelis-Menten kinetics, but the presence of the inhibitor shifts the curve to the right, indicating a decrease in affinity.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because competitive inhibition does not involve a permanent alteration of the enzyme's structure or activity. The enzyme remains functional, but is simply unable to bind to the substrate as effectively.

**Option B:** This option is incorrect because competitive inhibition can be overcome by increasing the concentration of the substrate. This is because the substrate can outcompete the inhibitor for binding to the active site, thereby restoring the enzyme's activity.

**Option C:** This option is incorrect because competitive inhibition is typically reversible. The inhibitor binds to the enzyme, but does not covalently modify it, and can be removed by diluting the reaction mixture or adding a high concentration of substrate.

**Clinical Pearl / High-Yield Fact**
A key feature of competitive inhibition is that it can be overcome by increasing the substrate concentration, making it a useful therapeutic strategy in cases where the substrate is present in high concentrations.

**Correct Answer: D**