**Core Concept**
Inverse agonism is a phenomenon where a ligand binds to the same receptor as an agonist but reduces the receptor's basal activity, often resulting in a pharmacological effect opposite to that of the agonist. This concept is crucial in pharmacology, as it highlights the complexity of receptor-ligand interactions and the potential for inverse agonists to modulate receptor activity in the absence of an agonist.

**Why the Correct Answer is Right**
The correct answer, **B. Binds to the same receptor binding-site as an agonist for that receptor but exerts the opposite pharmacological effect**, accurately describes the mechanism of inverse agonism. When an inverse agonist binds to the same receptor as an agonist, it induces a conformational change in the receptor that reduces its activity, often resulting in a decrease in the receptor's basal activity. This is in contrast to antagonists, which block agonist-induced receptor activity without altering the receptor's basal activity. The binding of an inverse agonist to the same receptor site as an agonist is a critical aspect of its mechanism, as it highlights the ligand's ability to modulate receptor activity in the absence of an agonist.

**Why Each Wrong Option is Incorrect**
* **Option A:** Action on the target receptors is similar to that of agonist - This statement is incorrect because inverse agonists do not mimic the agonist's effect; instead, they reduce the receptor's basal activity, often resulting in a pharmacological effect opposite to that of the agonist.
* **Option C:** Effective against receptors having intrinsic activity without acting of a ligand upon them - This statement is incorrect because inverse agonists do act on the receptor by binding to it, but they reduce the receptor's activity rather than enhancing it. Intrinsic activity refers to the receptor's ability to produce a response in the absence of an agonist, which is not directly related to inverse agonism.

**Clinical Pearl / High-Yield Fact**
Inverse agonists can be useful in treating conditions where an agonist would exacerbate the symptoms. For example, inverse agonists of the GABA_A receptor, such as flumazenil, are used to reverse the effects of benzodiazepine overdose. Understanding the concept of inverse agonism is crucial in developing targeted therapies for various conditions.

**✓ Correct Answer: B. Binds to the same receptor binding-site as an agonist for that receptor but exerts the opposite pharmacological effect**

✓ Correct Answer: B. Binds to the same receptor binding-site as an agonist for that receptor but exerts the opposite pharmacological effect