This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Biochemistry
Zwitterions are examples of 
Select and explain. 
A. Anions, B. Cations, C. Neutral ions, D. None of the above
C: Neutral ions
Answer: C: Neutral ions 
Explanation: Molecules that contain an equal number of positively and negatively charged groups bear no net charge. These ionized neutral species are termed zwitterions.
Zwitterions are one example of an isoelectric species the form of a molecule that has an equal number of positive and negative charges and thus is electrically neutral.
Ref: Harper’s illustrated biochemistry. 30th edition page no: 20