**Core Concept**
Neutrophil Extracellular Traps (NETs) are a network of extracellular fibers produced by neutrophils, a type of white blood cell, in response to infection or inflammation. NETs play a crucial role in trapping and killing pathogens, such as bacteria and fungi, by ensnaring them in a mesh of DNA and protein.

**Why the Correct Answer is Right**
NETs are formed through a process called NETosis, which involves the activation of neutrophils and the release of histones, a type of protein that binds to DNA. The histones are then decondensed, allowing the DNA to unwind and form a network of fibers. This process is mediated by the enzyme peptidylarginine deiminase 4 (PAD4), which deiminates histones, making them more susceptible to decondensation. The NETs then capture and kill pathogens through a combination of physical entrapment and the release of antimicrobial peptides and enzymes.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because it does not accurately describe the process of NET formation. While neutrophils do play a key role in NETosis, the process involves the release of histones and the decondensation of DNA, not the release of granules.
**Option B:** This option is incorrect because it suggests that NETs are only formed in response to bacterial infections, when in fact NETs can be formed in response to a variety of pathogens, including fungi and viruses.
**Option C:** This option is incorrect because it does not accurately describe the role of PAD4 in NET formation. While PAD4 does play a role in NETosis, it is not the only enzyme involved in the process.

**Clinical Pearl / High-Yield Fact**
NETs are an important part of the innate immune response, but they can also contribute to tissue damage and disease if not properly regulated. For example, NETs have been implicated in the pathogenesis of autoimmune disorders such as lupus and rheumatoid arthritis.

**Correct Answer:** D.