The varicella vaccine, commonly known as the chicken pox vaccine, contains a weakened version of the varicella zoster virus. The weakened version of the varicella zoster virus is the __________ in the vaccination.

• A. Antigen agent.
• B. Infecting agent.
• C. Immunizing agent.
• D. Vaccination agent.

Answer: (C)

Verified step by step guidance

1. Understand the role of the weakened virus in the vaccine: it is introduced to stimulate the immune system without causing the full disease.
2. Recall that the term 'immunizing agent' refers to the component in a vaccine that triggers an immune response to build immunity.
3. Differentiate between the options: 'antigen agent' refers to the part recognized by the immune system, 'infecting agent' would cause disease, and 'vaccination agent' is not a standard term.
4. Recognize that the weakened virus in the varicella vaccine acts as the immunizing agent because it safely induces immunity.
5. Conclude that the correct term for the weakened virus in the vaccine is the 'immunizing agent.'