**Core Concept**
Apoptosis, also known as programmed cell death, is a vital physiological process that eliminates unwanted or damaged cells from the body. This process is essential for normal development, tissue homeostasis, and maintaining the integrity of the immune system.

**Why the Correct Answer is Right**
Apoptosis is characterized by a series of distinct morphological and biochemical changes, including **cell shrinkage**, **chromatin condensation**, **DNA fragmentation**, and **membrane blebbing**. These changes are mediated by a family of cysteine proteases called **caspases**, which are activated in a cascade-like manner. The process of apoptosis is tightly regulated by a complex interplay of pro-apoptotic and anti-apoptotic proteins, ensuring that only unwanted cells are eliminated.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because apoptosis is indeed characterized by **cell shrinkage**, which is a hallmark of this process.
**Option C:** This option is incorrect because **DNA fragmentation** is a key feature of apoptosis, resulting from the activation of caspases and the breakdown of DNA into smaller fragments.

**Clinical Pearl / High-Yield Fact**
One important aspect of apoptosis is its role in maintaining immune tolerance, as it eliminates autoreactive T cells and prevents autoimmune disease. Additionally, dysfunction of the apoptotic pathway has been implicated in various diseases, including cancer and neurodegenerative disorders.

**Correct Answer: D.**