**Core Concept:** Morphine is an opioid analgesic, a potent agonist of mu-opioid receptors, commonly used for pain relief. However, we want to find a specific antagonist for it.

**Why the Correct Answer is Right:** The correct answer is Naloxone (D). Naloxone is a specific opioid receptor antagonist, also known as Narcotic Antagonist. It acts as a competitive antagonist, blocking the binding of Morphine and other opioids to their receptors, effectively reversing their effects.

**Why Each Wrong Option is Incorrect:**

A. Naloxone is not the correct antagonist for Morphine as mentioned above; instead, it is the correct antagonist.

B. Naloxone does not block the binding of other opioids, such as Codeine or Tramadol, to their receptors. These opioids have different receptor binding profiles than Morphine.

C. Naloxegol is an opioid partial agonist, not an antagonist. It acts as a partial agonist at mu receptors, which is different from the antagonist function of Naloxone.

D. Naltrexone is another opioid receptor antagonist, but it is not specific to Morphine. Naltrexone blocks the effects of all opioids, not just Morphine.

**Clinical Pearl/High-Yield Fact:**

Understanding opioid receptor antagonists is crucial for managing opioid-induced respiratory depression and other adverse effects. Naloxone is essential for reversing the respiratory depression and other adverse effects of opioids in emergency situations, ensuring patient safety.

**Correct Answer:** .