**Core Concept**
"Undoing" is a defense mechanism proposed by Sigmund Freud, where an individual attempts to undo or neutralize a previous unacceptable behavior or thought by engaging in a contradictory action or behavior. This mechanism is often used to alleviate feelings of guilt, anxiety, or discomfort associated with the original behavior.

**Why the Correct Answer is Right**
The defense mechanism of "undoing" typically involves an individual performing a contradictory action to negate the effects of their previous behavior. For instance, if someone has been aggressive towards someone, they might subsequently engage in an act of kindness or generosity to "undo" their earlier behavior. This mechanism is thought to be a way of restoring balance and reducing feelings of guilt or anxiety. The contradictory action serves as a form of psychological compensation, attempting to erase the negative effects of the original behavior.

**Why Each Wrong Option is Incorrect**
* **Option A:** This option is not relevant to the defense mechanism of "undoing".
* **Option B:** This option is incorrect as it describes a different defense mechanism, such as "repression".
* **Option C:** This option is not directly related to the defense mechanism of "undoing".

**Clinical Pearl / High-Yield Fact**
It's essential to recognize that defense mechanisms can be adaptive in certain situations but maladaptive in others. Understanding these mechanisms can help clinicians better assess and treat patients with psychological distress.

**Correct Answer: D**