**Core Concept**
Projection is a defense mechanism where an individual attributes their unacceptable thoughts, feelings, or motives to someone else. This concept is essential in understanding human behavior and psychological dynamics.

**Why the Correct Answer is Right**
In the context of projection, an individual shifts the blame from themselves to others, thereby avoiding feelings of guilt, shame, or responsibility. This defense mechanism is often seen in individuals with low self-esteem or those who struggle with accountability. Projection can manifest in various ways, such as accusing others of one's own flaws or attributing one's own unacceptable thoughts to someone else. For instance, a person who is jealous might accuse their partner of being unfaithful, thereby projecting their own insecurities onto their partner.

**Why Each Wrong Option is Incorrect**
**Option A:** Rationalization is a defense mechanism where an individual creates logical excuses to justify their unacceptable behavior. While rationalization can involve blaming others, it is not the primary mechanism of shifting blame onto someone else.
**Option B:** Compensation is a defense mechanism where an individual overachieves in one area to make up for a perceived weakness or inadequacy. This mechanism does not involve blaming others for one's mistakes.
**Option D:** Regression is a defense mechanism where an individual reverts to an earlier stage of development, often as a coping mechanism for stress or anxiety. Regression does not involve blaming others for one's mistakes.

**Clinical Pearl / High-Yield Fact**
It's essential to recognize that defense mechanisms can be adaptive in the short term but maladaptive in the long term. Projection, in particular, can lead to strained relationships and difficulty in taking responsibility for one's actions.

**✓ Correct Answer: C. Projection. It is a defense mechanism where an individual attributes their unacceptable thoughts, feelings, or motives to someone else.**