This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Communicable diseases, Subject name: Social & Preventive Medicine
The adjuvant used in DPT vaccine is - 
Select and explain. 
A. A1, B. Mg, C. Zn, D. Formaldehyde
A: A1
Answer: A: A1 
Explanation: Adsorption of DPT vaccine on a mineral carrier like aluminium phosphate or hydroxide increases the immunological effectiveness of vaccine. Ref:PARK&;S TEXTBOOK OF PREVENTIVE AND SOCIAL MEDICINE 23rd edition , Page :162