Vaccination is carried out in order to

Step 1: Analyze the question The question asks about the main purpose of vaccination.

Step 2: The concept A vaccine contains a weakened or killed pathogen, or part of one (an antigen). When it is introduced into the body:

1. The immune system recognizes the antigen as foreign.
2. White blood cells (B-lymphocytes) produce antibodies against it.
3. Memory cells remain in the body. If the real pathogen enters later, the body responds quickly and strongly, so you don't fall ill. This is called active artificial immunity.

Step 3: Evaluate the options

• A. Check the production of poison: Wrong. This describes the action of an antitoxin, not the purpose of a vaccine.
• B. Increase the activities of white blood cells: This is partly true, since lymphocytes are involved. But it is too general. The specific, direct aim of vaccination is to get the body to make antibodies.
• C. Increase the number of red blood cells: Wrong. Red blood cells carry oxygen and are not involved in immunity.
• D. Stimulate the production of antibodies: Correct. This is the precise purpose of vaccination.

Step 4: Answer The correct option is D.

Exam tip: Remember "Vaccine = Antigen in, Antibodies out." When you see "vaccination" or "immunization" in a question, look for the option with antibodies in it. Also remember that vaccination gives active immunity (your body makes its own antibodies), while an injection of ready-made antibodies gives passive immunity.