## Core Concept
Inverse agonism refers to the phenomenon where a compound binds to the same receptor as an agonist but induces a pharmacological response opposite to that of the agonist. This occurs by reducing the constitutive activity of the receptor, which is the activity the receptor exhibits in the absence of any ligand.

## Why the Correct Answer is Right
The correct answer, ., implies that constitutive activity reduction is a key feature of inverse agonism. Inverse agonists work by decreasing the receptor's activity below the baseline level observed in the absence of any ligand. This is different from antagonists, which merely block agonist action without affecting the receptor's baseline activity.

## Why Each Wrong Option is Incorrect
- **Option A:** If option A describes a feature such as "reduces receptor activity below baseline," it would actually align with the definition of inverse agonism and thus be incorrect as an "except" option.
- **Option B:** If option B mentions "binds to the receptor," this is a characteristic of inverse agonism, as inverse agonists do bind to the receptor. Therefore, it's not the correct "except" option.
- **Option C:** If option C talks about "opposite effect of agonist," this is indeed a feature of inverse agonism. Hence, it's incorrect as an exception.

## Clinical Pearl / High-Yield Fact
A key clinical pearl is that inverse agonists have the potential to be more than just blockers; they can actually decrease the activity of a receptor below its normal level. This concept is crucial in understanding the treatment of certain conditions, such as the use of beta-blockers in heart failure, where some beta-blockers exhibit inverse agonism at certain receptors.

## Correct Answer: D.