**Core Concept**
Apoptosis is a form of programmed cell death, a highly regulated process that eliminates damaged or unwanted cells from the body. It is characterized by a series of morphological and biochemical changes that ultimately lead to the fragmentation of the cell into apoptotic bodies.

**Why the Correct Answer is Right**
Apoptosis is a form of cell death that is distinct from necrosis, and it is characterized by several key features, including **cell shrinkage**, **chromatin condensation**, **DNA fragmentation**, and **phagocytosis of apoptotic bodies**. These changes occur due to the activation of a cascade of proteolytic enzymes, including caspases, which are responsible for the breakdown of cellular components.

**Why Each Wrong Option is Incorrect**
**Option A:** Cell lysis is a feature of necrosis, not apoptosis. In apoptosis, the cell membrane remains intact, and the cell is engulfed by phagocytic cells.
**Option B:** Mitochondrial outer membrane permeabilization is a key event in apoptosis, leading to the release of cytochrome c and the activation of caspases.
**Option C:** DNA fragmentation is a hallmark of apoptosis, occurring due to the activation of endonucleases that cleave the DNA into smaller fragments.

**Clinical Pearl / High-Yield Fact**
It's essential to note that apoptosis is a critical process in maintaining tissue homeostasis and preventing cancer. Dysregulation of apoptosis has been implicated in various diseases, including cancer, neurodegenerative disorders, and autoimmune diseases.

**Correct Answer:** A. Cell lysis.