**Core Concept**
DNA molecules in their native state are highly negatively charged due to the presence of phosphate groups. At physiological pH (around 7.4), the phosphate groups in DNA have a negative charge, making DNA a polyanion. This charge affects the structure and function of DNA.

**Why the Correct Answer is Right**
The phosphate groups in DNA are responsible for its negative charge. At physiological pH, the phosphate groups are deprotonated, meaning they have lost a proton (H+ ion), resulting in a negative charge. This charge is crucial for the interaction of DNA with other molecules, such as histones, and for its overall structure and function. The negative charge of DNA also allows it to interact with positively charged molecules, such as proteins.

**Why Each Wrong Option is Incorrect**
**Option A:** Incorrect because DNA is not a polycation at physiological pH. While DNA does have some positive charges from the nitrogenous bases, these charges are not sufficient to make DNA a polycation.
**Option B:** Incorrect because DNA is not neutral at physiological pH. The phosphate groups in DNA are deprotonated, resulting in a negative charge.
**Option C:** Incorrect because DNA is not a zwitterion at physiological pH. A zwitterion is a molecule with both positive and negative charges, but DNA does not have a significant positive charge at physiological pH.

**Clinical Pearl / High-Yield Fact**
DNA's negative charge is essential for its interaction with other molecules, such as histones, and for its overall structure and function. This charge is also important for the process of DNA replication and transcription.

**Correct Answer: B. Negatively charged.**